lang/gcc11: Revert "Fix conflict on libgccjit.h and libgccjit++.h"

This reverts commit dc67e7d3009de2b78d96136c8ad09cf186e553df.

The revert is necessary as

• lang/gcc11/files/patch-gcc_Makefile.in was wrong: it should have used $(version) instead of $(gcc_version);

• even after correcting the above mistake, the patch still does not work: lang/emacs fails to configure and hence to build. See also https://reviews.freebsd.org/D37266 .

PR: 257060
Reported by: yasu