XL: Restore suppression of infinite loop warning in process test

Our use of the `-qsuppress=` flag to suppress this warning was removed
by commit 51e95ba7 (XL: Fix compatibility with newer clang-based XL on
Linux, 2017-04-28) because XL 13.1.[1-6] for Linux does not support the
flag.  XL 16.1 restores support for the flag.  Restore our use of it for
this version.  Suppress the warning on intermediate versions by blocking
all warnings with `-w`.

CMakeLists.txt

@@ -1193,13 +1193,17 @@ IF(KWSYS_STANDALONE OR CMake_SOURCE_DIR)
     # Some Apple compilers produce bad optimizations in this source.
     IF(APPLE AND CMAKE_C_COMPILER_ID MATCHES "^(GNU|LLVM)$")
       SET(testProcess_COMPILE_FLAGS "${testProcess_COMPILE_FLAGS} -O0")
-    ELSEIF(CMAKE_C_COMPILER_ID STREQUAL "XL" AND
-           NOT (CMAKE_SYSTEM MATCHES "Linux.*ppc64le" AND
-                NOT CMAKE_C_COMPILER_VERSION VERSION_LESS "13.1.1"))
+    ELSEIF(CMAKE_C_COMPILER_ID STREQUAL "XL")
       # Tell IBM XL not to warn about our test infinite loop
-      # v13.1.1 and newer on Linux ppc64le is clang based and does not accept
-      # the -qsuppress option
-      SET(testProcess_COMPILE_FLAGS "${testProcess_COMPILE_FLAGS} -qsuppress=1500-010")
+      IF(CMAKE_SYSTEM MATCHES "Linux.*ppc64le"
+         AND CMAKE_C_COMPILER_VERSION VERSION_LESS "16.1.0"
+         AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS "13.1.1")
+        # v13.1.[1-6] on Linux ppc64le is clang based and does not accept
+        # the -qsuppress option, so just suppress all warnings.
+        SET(testProcess_COMPILE_FLAGS "${testProcess_COMPILE_FLAGS} -w")
+      ELSE()
+        SET(testProcess_COMPILE_FLAGS "${testProcess_COMPILE_FLAGS} -qsuppress=1500-010")
+      ENDIF()
     ENDIF()
     IF(CMAKE_C_FLAGS MATCHES "-fsanitize=")
       SET(testProcess_COMPILE_FLAGS "${testProcess_COMPILE_FLAGS} -DCRASH_USING_ABORT")