[LLDB] [LoongArch] Add loongarch64 case in ComputeHostArchitectureSupport()

[seehearfeel]

Summary

This is a simple change, loongarch64 host also supports 32-bit binaries,
so note it.

Without this patch:

[loongson@linux build]$ ./tools/lldb/unittests/Host/HostTests | tail -6
[==========] 78 tests from 18 test suites ran. (16 ms total)
[  PASSED  ] 77 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] HostTest.GetProcessInfo

 1 FAILED TEST

With this patch:

[loongson@linux build]$ ./tools/lldb/unittests/Host/HostTests | tail -2
[==========] 78 tests from 18 test suites ran. (15 ms total)
[  PASSED  ] 78 tests.

[xen0n]

Trivially correct. CONFIG_COMPAT isn't yet supported by upstream Linux though, but preemptively adding LoongArch here won't do any harm.

[DavidSpickett]

LGTM. Follows the same logic AArch64 does. (meaning: we don't support debugging 32 bit from a 64 bit lldb very well, if it all, but it's still noted here as possible)

lldb/source/Host/common/HostInfoBase.cpp

default:
     arch_32.SetTriple(triple);
     break;
 
   case llvm::Triple::aarch64:
   case llvm::Triple::ppc64:
   case llvm::Triple::ppc64le:
   case llvm::Triple::x86_64:
   case llvm::Triple::riscv64:
+  case llvm::Triple::loongarch64:
     arch_64.SetTriple(triple);
     arch_32.SetTriple(triple.get32BitArchVariant());
     break;
 
   case llvm::Triple::mips64:
   case llvm::Triple::mips64el:
   case llvm::Triple::sparcv9:
   case llvm::Triple::systemz:
     arch_64.SetTriple(triple);
     break;
   }
 }