[NFC][compiler-rt] Add ppc32 to the list of arch

This should have been done when it was added to the symmetrical list in
the builtins config-ix in D87383, but it was overlooked.

Author: daltenty

compiler-rt/cmake/config-ix.cmake

@@ -277,6 +277,7 @@ set(X86 i386)
 set(X86_64 x86_64)
 set(MIPS32 mips mipsel)
 set(MIPS64 mips64 mips64el)
+set(PPC32 powerpc)
 set(PPC64 powerpc64 powerpc64le)
 set(RISCV32 riscv32)
 set(RISCV64 riscv64)