[compiler-rt] Found one more delta to unbreak build for z/os (PR #82789)

[Alexander Richardson via llvm-commits]

================
@@ -756,8 +756,15 @@ set(riscv64_SOURCES
   ${riscv_SOURCES}
 )
 
-set(sparc_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
-set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+# Exclude the FT sources for 32-bit SPARC.  Clang doesn't
+# support 128-bit long double on 32-bit SPARC.
+if("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "sparc")
+  set(sparc_SOURCES ${GENERIC_SOURCES})
+  set(sparcv9_SOURCES ${GENERIC_SOURCES})
+else()
+  set(sparc_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+  set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+endif()
----------------
arichardson wrote:

I don't quite understand this conditional. Why do we need to check `COMPILER_RT_DEFAULT_TARGET_ARCH`?

Also is the sparcv9 build 32-bit? If not could this be simplified to:
```suggestion
set(sparc_SOURCES ${GENERIC_SOURCES})
set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
```

https://github.com/llvm/llvm-project/pull/82789