[clang][RISCV][test] Add more tests of the -mabi and -march options
- There is no tests for mabi=ilp32e, and my patch covers that.
- The tests in riscv-abi.c will show default ABI changes for special archs in the future, especially the arch with the F but without the D extension.
- The tests in riscv-arch.c will show default arch changes for abi=ilp32, which is rv32imacfd currently, but it is better to be rv32imac. And it is also better for abi=ilp32f defaults to arch=imacf.
Reviewed By: MaskRay, luismarques
Differential Revision: https://reviews.llvm.org/D103878