requirements.c using va_list, but not including stdarg.h
make src-check on S3_0 reveals:
# C or C++ files which use va_list but don't include stdarg.h: common/requirements.c
S2_6 not affected, all other branches are.
make src-check on S3_0 reveals:
# C or C++ files which use va_list but don't include stdarg.h: common/requirements.c