nocompile-limits.dfa: turns off all limits including run-time limits
nolimits.dfa: makes the compile time limits unlimited while leaving on
the run-time limits.
Fixes compiler warnings exposed by these tests. These are just warnings,
there were no bugs other than a failure to handle systems with a 16-bit
at the appropriate time which would result in a later failure on malloc.
png.c: png_icc_check_length: in-line code was still used in place of
png_chunk_max when checking the current chunk allocation limit. The
in-line code did not handle PNG_MAXSEG_64K and, anyway, issued
compiler warnings in the 'nocompile-limits' case. Changed to use
png_malloc_max.
pngrutil.c: eliminated an erroneous 'truncation' warning with GCC-14 by
using a safe cast.
pngtest.c: failed to check for PNG_USER_LIMITS_SUPPORTED around API
calls which don't exist without PNG_USER_LIMITS.
Signed-off-by: John Bowler <jbowler@acm.org>
