libical: Do not set CC explicitly for gir compiler

libical: Do not set CC explicitly for gir compiler

This ensures that right sysroot is used during build, otherwise we see
warnings in build about using wrong sysroot and it fails explicitly with
clang

x86_64-yoe-linux-ld: warning: library search path "/usr/lib/gcc/x86_6
4-pc-linux-gnu/11.2.0/../../../../lib64" is unsafe for cross-compilation

x86_64-yoe-linux-ld: cannot find /usr/lib/clang/14.0.0/lib/linux/libc
lang_rt.builtins-x86_64.a: No such file or directory

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>