New package: llvm12-12.0.0

Distro changes since 11.0:

- html docs are now included (except lldb where they are broken)
- manpages are now included
- enabled linker build id
- libcxx(abi), libunwind, libomp are now built as subpackages
- disabled clangd on ppc32 (crashes assembler)
- template cleanups

Cross fixes by Leah.

Closes https://github.com/void-linux/void-packages/issues/28609
Closes https://github.com/void-linux/void-packages/issues/17935

common/shlibs

@@ -984,10 +984,11 @@ libuchardet.so.0 uchardet-0.0.6_1
 libgtksourceviewmm-3.0.so.0 gtksourceviewmm-3.2.0_1
 libyajl.so.2 yajl-2.0.1_1
 libconfuse.so.2 confuse-3.2.1_1
-liblldb.so.11 lldb-11.0.0_1
-libclang.so.11 libclang-11.0.0_1
-libclang-cpp.so.11 libclang-cpp-11.0.0_1
+liblldb.so.12 lldb-12.0.0_1
+libclang.so.12 libclang-12.0.0_1
+libclang-cpp.so.12 libclang-cpp-12.0.0_1
 libLLVM-11.so libllvm11-11.0.0_1
+libLLVM-12.so libllvm12-12.0.0_1
 libisofs.so.6 libisofs-0.6.24_1
 libmpack.so.0 libmpack-1.0.5_1
 libGeoIP.so.1 libgeoip-1.4.8_1