[cmake] Modernize some conditionals. NFC

The "x${...}" form was a workaround for CMake versions prior to 3.1,
where the if command would interpret arguments as variables even when
quoted [1]. We can drop the workaround now that our minimum CMake
version is 3.4.

[1] https://cmake.org/cmake/help/v3.1/policy/CMP0054.html

Differential Revision: https://reviews.llvm.org/D40744

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319723 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/modules/LLVM-Config.cmake

@@ -99,9 +99,9 @@ function(explicit_llvm_config executable)
 
   llvm_map_components_to_libnames(LIBRARIES ${link_components})
   get_target_property(t ${executable} TYPE)
-  if("x${t}" STREQUAL "xSTATIC_LIBRARY")
+  if(t STREQUAL "STATIC_LIBRARY")
     target_link_libraries(${executable} INTERFACE ${LIBRARIES})
-  elseif("x${t}" STREQUAL "xSHARED_LIBRARY" OR "x${t}" STREQUAL "xMODULE_LIBRARY")
+  elseif(t STREQUAL "SHARED_LIBRARY" OR t STREQUAL "MODULE_LIBRARY")
     target_link_libraries(${executable} PRIVATE ${LIBRARIES})
   else()
     # Use plain form for legacy user.