[clang] [clang][LoongArch] Add OHOS target (PR #127555)

[Fangrui Song via cfe-commits]

================
@@ -0,0 +1,16 @@
+/// Check the max-page-size for OHOS aarch64/loongarch64/riscv64/x86_64.
----------------
MaskRay wrote:

Don't add a new file for a minor property (though important to test) like page-size. Just reuse ohos.c

Many driver tests are probably not organized in the best way. linux-cross.cpp could give inspiration.
You usually need to `rg max-page-size clang/test/Driver`, read multiple tests , and decide how to write the test in the most elegant way:)

https://github.com/llvm/llvm-project/pull/127555