Changes

utils: Update guard checks in config.h
Since glibc 2.38 the functions strchrnul and strcasestr have been 
exposed by default, rather than being hidden behind _GNU_SOURCE.
We therefore use the GLIBC_PREREQ macro to check the version of the
glibc headers and do not accidentally double-declare these functions.
Signed-off-by: Daniel Silverstone <dsilvers@netsurf-browser.org>

utils: Update config.h for confusing define problems
For some reason, we have to use the __GLIBC_PREREQ macro in a more
confined way otherwise the preprocessor gets confused.
Signed-off-by: Daniel Silverstone <dsilvers@netsurf-browser.org>

utils: Belt and braces to satisfy gcc
GCC was upset that it was theoretically possible for this format string
to result in a buffer overrun.  This is because it could not work out
that `i` would never be negative. To silence the warning, we use %u and
cast to unsigned during the formatting of the output filename.
Signed-off-by: Daniel Silverstone <dsilvers@netsurf-browser.org>

monkey: Fix off-by-one which could result in overflow
The buffer for storing the js_exec arguments could be one byte too small
in which case bad things might happen.  This fixes that.
Signed-off-by: Daniel Silverstone <dsilvers@netsurf-browser.org>

js: duktape bindings: Squash -Wcalloc-transposed-args (gcc-14)

fetch: Squash -Wcalloc-transposed-args (gcc-14)

image handlers: Squash -Wcalloc-transposed-args (gcc-14)

content caches: Squash -Wcalloc-transposed-args (gcc-14)

desktop: textarea: Squash -Wcalloc-transposed-args (gcc-14)

frontends: monkey: Squash -Wcalloc-transposed-args (gcc-14)

nsurl: Reject URLs with invalid host components
The host component, by the time we hit the validation code, should be a
valid DNS name.  In theory it could also be an IPv6 address, but those
are far more painful to deal with so we're ignoring that opportunity for
now.
This fixes a problem where the search_web_omni logic would fail to
generate a search because nsurl_create() succeeded even though it
shouldn't have.
Signed-off-by: Daniel Silverstone <dsilvers@netsurf-browser.org>

Change env script to use posix command -v

Change env script help text display

nsurl: Add underscore to permitted characters
The host component must be a valid DNS name; and unfortunately 
underscores are present in some DNS names already, despite a 2019 
decision to not issue them going forward.  As such we permit the 
underscore as well in order to work with old-school URLs which may exist
in the wild.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

test: Correct nsurl case which should fail
We were previously assuming a badly escaped hostname would not be a url
parse failure; but in practice firefox expects it to fail and thus omnis
to a search instead.  This behaviour is expected, thus we update the
test case.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

nsurl: Add support for IPv6 literals
Unfortunately, despite previous assertions to the contrary, we do need
to deal with IPv6 literals.  For now we validate just that they are
encased by square brackets and consist only of hex digits and colons. 
We do not validate that they are actually valid IPv6 addresses.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

Ensure perl tool expansion is used everywhere

html: layout: FPCT_OF_INT_TOINT is now in LibCSS

css, html: Update to new LibCSS css_computed_width API
Currently using the static variant, but in future we'll switch to using
the one that resolves to pixels for us.

calc(): layout: minmax table: Use new css width getter API

calc(): layout: minmax line: Use new css width getter API

calc(): layout: minmax block: Use new css width getter API

calc(): layout: table: Use new css width getter API

calc(): layout: find dimensions: Use new css width getter API

content: css: dump: Handle CALC unit type
We won't actually reach this, because the type won't be SET if it's
CALC.

move core window callbacks to the standard gui tables

improve treeview creation to not modify output parameter on error

fix atari frontend after core window changes

test: calc: Add pages that use calc for width property

utils: Add clamp() macro
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

box_construct: clamp rowspan and colspan
In order to not blow up on massive rowspan/colspan values (which could
be an issue according to #2873) we clamp them according to the HTML spec
section 4.9.11
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

nsurl: Correctly return non-IDNA hosts
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

nsurl: Free host if nomem encountered
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

idna: Bounds check during encode/decode
Detected by some norwegian students who were doing security analysis, we
would overrun buffers in idna_{en,de}code() so this corrects that
problem.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

test: Add nsurl test to cover idna_{en,de}code()
This adds regression checks for the security issue recently fixed in
idna_{en,de}code().
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

idna: use memcpy not strncpy
Since we know the number of bytes we want to copy, just use memcpy 
instead of strncpy - this will be faster and hopefully will warn less on
arm systems.
Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

html: css: Update to new css_computed_width API

change web search option to use provider name instead of index