If you want to mess with the compiler options (i.e. what you'd get with perl -V:ccflags), you can edit the respective entry in Config.pm, or more specifically Config_heavy.pl.

Run the following command to find out where those files are located:

perl -MConfig -E "say $Config{ccflags}; say for sort values %INC"
[download]

(I'm not convinced this will get you anywhere, but as you asked...   And don't forget to make a backup copy first.)