crtl stdint.h: missing INTn_C / UINTn_C / INTMAX_C constant macros

• Type: bug (crtl header gap). Track B (lib/crtl) — filed from Track A's night session per lane rules; C-frontend token-paste in this position may need a Track C look if the obvious define fails.
• Status: done
• Opened: 2026-07-14 night, the wall AFTER alloca in the QuickJS bring-up ([[feature-c-corpus-quickjs]]).

Symptom

pascal26:18884: error: call to undeclared function: UINT64_C ()
  near: radixl  UINT64_C

QuickJS's libbf uses UINT64_C(0x...) for its radix tables. C99 requires stdint.h to provide INT8_C..INTMAX_C / UINT8_C..UINTMAX_C.

Fix shape

In lib/crtl/include/stdint.h:

#define INT8_C(c)    c
#define INT16_C(c)   c
#define INT32_C(c)   c
#define INT64_C(c)   c ## LL
#define UINT8_C(c)   c
#define UINT16_C(c)  c
#define UINT32_C(c)  c ## U
#define UINT64_C(c)  c ## ULL
#define INTMAX_C(c)  c ## LL
#define UINTMAX_C(c) c ## ULL

Needs cpreproc ## token paste on a macro ARG followed by a suffix — the paste-rescan arc (b184-188, tcc bring-up) landed that machinery; verify it handles c ## ULL where c is a hex literal.

Acceptance

• UINT64_C(0x123) in a pxx-compiled C file equals 0x123ULL (gcc parity).
• QuickJS unity build compiles past line ~18884 (next wall surfaces).

Log

• 2026-07-15 — resolved, commit 25a0499c.