Prefer BSD uuid over libuuid

Prefer BSD uuid over libuuid

This fixes recent NetBSDbuild breakage:
../libcoreclrpal.a(miscpalapi.cpp.o): In function `CoCreateGuid':
/tmp/pkgsrc-tmp/wip/coreclr-git/work/coreclr/src/pal/src/misc/miscpalapi.cpp:356: undefined reference to `uuid_generate_random'
clang-3.9: error: linker command failed with exit code 1 (use -v to see invocation)

No need to link against libuuid.

Add detection of BSD-styl <uuid.h>.
Few Linux distros ship with custom <uuid.h> and they aren't compatibile.

Commit migrated from https://github.com/dotnet/coreclr/commit/d981e1b43617bdd6fc3d34dbde8c53169e52d0ab