Compiler-rt: Fix MIPS CMake variables set

[wzssyqa]

Summary

Move the code which set CMake variables for MIPS to
compiler-rt/cmake/base-config-ix.cmake from compiler-rt/CMakeLists.txt.

compiler-rt/CMakeLists.txt includes compiler-rt/cmake/base-config-ix.cmake
very early. If the variables are set in compiler/CMakeLists.txt,
compiler-rt/cmake/base-config-ix.cmake cannot use them.

[jrtc27]

Please include context; see https://llvm.org/docs/Phabricator.html#phabricator-request-review-web

[wzssyqa]

In D157900#4585658, @jrtc27 wrote:

Please include context; see https://llvm.org/docs/Phabricator.html#phabricator-request-review-web

Done.

[wzssyqa]

@MaskRay ping

compiler-rt/CMakeLists.txt

     CHECK_SYMBOL_EXISTS (__thumb__ "" COMPILER_RT_ARM_THUMB)
   endif()
 endif()
-if (${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "^mips")
-  CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS32R6 "" COMPILER_RT_MIPS32R6)
-  CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS64R6 "" COMPILER_RT_MIPS64R6)
-  CHECK_SYMBOL_EXISTS (__mips64 "" COMPILER_RT_MIPS_64)
-  CHECK_SYMBOL_EXISTS (__MIPSEL__ "" COMPILER_RT_MIPS_EL)
-  if ("${COMPILER_RT_MIPS_64}")
-    set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips64")
-  else()
-    set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips")
-  endif()
-  if ("${COMPILER_RT_MIPS_EL}")
-    set(COMPILER_RT_DEFAULT_TARGET_ARCH "${COMPILER_RT_DEFAULT_TARGET_ARCH}el")
-  endif()
-endif()
 if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*android.*")
   set(ANDROID 1)
   string(REGEX MATCH "-target(=| +)[^ ]+android[a-z]*([0-9]+)" ANDROID_API_LEVEL "${CMAKE_C_FLAGS}")

compiler-rt/cmake/base-config-ix.cmake

       test_target_arch(sparc "" "-m32")
       test_target_arch(sparcv9 "" "-m64")
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "mips")
+      CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS32R6 "" COMPILER_RT_MIPS32R6)
+      CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS64R6 "" COMPILER_RT_MIPS64R6)
+      CHECK_SYMBOL_EXISTS (__mips64 "" COMPILER_RT_MIPS_64)
+      CHECK_SYMBOL_EXISTS (__MIPSEL__ "" COMPILER_RT_MIPS_EL)
+      if ("${COMPILER_RT_MIPS_64}")
+        set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips64")
+      else()
+        set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips")
+      endif()
+      if ("${COMPILER_RT_MIPS_EL}")
+        set(COMPILER_RT_DEFAULT_TARGET_ARCH "${COMPILER_RT_DEFAULT_TARGET_ARCH}el")
+      endif()
+
       # FIXME: Ideally, we would build the N32 library too.
       if("${COMPILER_RT_MIPS_EL}" AND ("${COMPILER_RT_MIPS32R6}" OR "${COMPILER_RT_MIPS64R6}"))
         test_target_arch(mipsel "" "-mips32r6" "-mabi=32" "-D_LARGEFILE_SOURCE=1" "-D_FILE_OFFSET_BITS=64")