[PROJ] -Wextra-semi breaking build with gcc7

[Greg Troxel]

CMakeLists.txt has

-Wextra-semi

but it does not validate that the compiler is ok with that option.
This leads to a failure on NetBSD 9 which has gcc 7.

For now I'm patching it out, but I wonder how cmake intends to deal with
this.  One can't assume that any particular nonstandard warning flags
are acceptable; I think each needs to have a trial compile and only be
added if that passes.  But I am not cmake-clueful enough to know how.


http://www.ki.nu/pkgsrc/reports/current/NetBSD-9.0/20240901.2232/proj-9.4.1/build.log