gcc: remove g77/f77

gcc: remove g77/f77

g77/f77 has been removed from gcc 4.0.0 via commit:

* b4117c30610 Makefile.def, [...]: Remove all mention of libf2c.

When set

    FORTRAN = ",f77"

it complains with error:

| The following requested languages could not be built: f77
| Supported languages are: c,c,c++,fortran,go,lto,m2,objc,obj-c++

So remove g77/f77 from gcc recipes.

[1]: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b4117c30610

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>