These instances were detected by searching for files that include
stdlib.h, but don't match the regex:
\\b(_abort|abort|abs|aligned_alloc|arc4random|arc4random_buf|arc4random_
uniform|atexit|atof|atoi|atol|atoll|bsearch|calloc|clearenv|div|div_t|ex
it|_Exit|EXIT_FAILURE|EXIT_SUCCESS|free|getenv|getprogname|grantpt|labs|
ldiv|ldiv_t|llabs|lldiv|lldiv_t|malloc|malloc_good_size|malloc_size|mble
n|mbstowcs|mbtowc|mkdtemp|mkstemp|mkstemps|mktemp|posix_memalign|posix_o
penpt|ptsname|ptsname_r|putenv|qsort|qsort_r|rand|RAND_MAX|random|reallo
c|realpath|secure_getenv|serenity_dump_malloc_stats|serenity_setenv|sete
nv|setprogname|srand|srandom|strtod|strtof|strtol|strtold|strtoll|strtou
l|strtoull|system|unlockpt|unsetenv|wcstombs|wctomb)\\b
(Without the linebreaks.)
This regex is pessimistic, so there might be more files that don't
actually use anything from the stdlib.
In theory, one might use LibCPP to detect things like this
automatically, but let's do this one step after another.
We were consuming all whitespace from the format, but not the input
lexer - that was left to the actual format parsing code. It so happened
that we did not account for whitespace with the conversion specifier
'[', causing whitespace to end up in the output variables.
Fix this by always consuming all whitespace and removing the whitespace
logic from the conversion code.
This was currently crashing Half-Life because it was a considered an
"Unknown" specifier. We can use the same case statement as the regular
hex format conversion (lower case 'x'), as the backend
to convert the number already supports upper/lower case input, hence
we get it for free :^)
Also add a test to prevent this from happening again. There were two
bugs:
* The number of bytes just after processing the last value was written,
instead of the number of bytes after skipping remaining whitespace.
Confirmed by testing against GNU's `scanf()` since the man page
leaves something to be desired.
* The number of bytes was written to the wrong variable argument; i.e.
the first argument was overwritten.
