memcmp is C89 and 4.3BSD

src/acconfig.h

src/builtin_functions.c

src/configure.in

src/lexer.h

src/modules/Parser/xml.cmod

src/pike_memory.c

src/pike_search_engine2.c

src/pike_threadlib.h

src/port.c

src/port.h

src/post_modules/GSSAPI/gssapi.cmod

src/stralloc.c

src/stralloc.h