[Bug c/105177] GCC should warn if pragma redefine_extname fails due to missing declaration

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105177

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is the Solaris compiler documentation about this feature since GCC is
supposed to be implementing them:
https://docs.oracle.com/cd/E37069_01/html/E37074/bjacu.html