android: add support for libLLVMFrontendOpenMP

android: add support for libLLVMFrontendOpenMP

Fixes the following building errors:

FAILED: out/soong/.intermediates/external/llvm-project/llvm/libLLVM10/android_x86_64_core_shared/unstripped/libLLVM10.so
ld.lld: error: undefined symbol: llvm::OpenMPIRBuilder::initialize()
...
ld.lld: error: undefined symbol: llvm::OpenMPIRBuilder::addAttributes(llvm::omp::RuntimeFunction, llvm::Function&)
...
ld.lld: error: undefined symbol: llvm::OpenMPIRBuilder::getOrCreateDefaultSrcLocStr()
...
ld.lld: error: undefined symbol: llvm::OpenMPIRBuilder::getOrCreateIdent(llvm::Constant*, llvm::omp::IdentFlag)
...
clang-9: error: linker command failed with exit code 1 (use -v to see invocation)

Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>