devel/electron12: fix build

In file included from ../../third_party/nasm/asm/assemble.c:178:
../../third_party/nasm/include/compiler.h:249:21: error: static declaration of 'mempcpy' follows non-static declaration
static inline void *mempcpy(void *dst, const void *src, size_t n)

^

/usr/include/string.h:70:7: note: previous declaration is here
void *mempcpy(void * restrict, const void * restrict, size_t);

^

PR: 257378
Reported by: Robert Cina <transitive@gmail.com>
Tested by: meta
Approved by: maintainer timeout (> 2 weeks)
MFH: 2021Q4

(cherry picked from commit 9cdeb88eac13fab9aed2f3972cef30d229890bde)