mpc does not honor $RPM_OPT_FLAGS, resulting in no-no such as no compiler
generated security features and more or less useless debuginfo.

Compilation output has gcc lines like:
gcc -DHAVE_CONFIG_H -I. -I. -I..   -Wall -I/usr/include  -Wall -I/usr/include -c
`test -f 'options.c' || echo './'`options.c
(No $RPM_OPT_FLAGS anywhere there)