libclc: Fix LLVM library linking on Windows

CMake requires library lists on Windows to be split by semi-colons,
rather than the spaces we get from llvm-config. Fix this by a
substitution on Windows.

reviewer: jvesely
Differential Revision: https://reviews.llvm.org/D77162

Author: fooishbar

libclc/CMakeLists.txt

@@ -58,9 +58,11 @@ list( SORT LIBCLC_TARGETS_TO_BUILD )
 execute_process( COMMAND ${LLVM_CONFIG} "--system-libs"
 	OUTPUT_VARIABLE LLVM_SYSTEM_LIBS
 	OUTPUT_STRIP_TRAILING_WHITESPACE )
+separate_arguments( LLVM_SYSTEM_LIBS )
 execute_process( COMMAND ${LLVM_CONFIG} "--libs" "core" "bitreader" "bitwriter"
 	OUTPUT_VARIABLE LLVM_LIBS
 	OUTPUT_STRIP_TRAILING_WHITESPACE )
+separate_arguments( LLVM_LIBS )
 execute_process( COMMAND ${LLVM_CONFIG} "--libdir"
 	OUTPUT_VARIABLE LLVM_LIBDIR
 	OUTPUT_STRIP_TRAILING_WHITESPACE )
@@ -76,7 +78,7 @@ execute_process( COMMAND ${LLVM_CONFIG} "--bindir"
 	OUTPUT_STRIP_TRAILING_WHITESPACE )
 
 # These were not properly reported in early LLVM and we don't need them
-set( LLVM_CXX_FLAGS ${LLVM_CXX_FLAGS} -fno-rtti -fno-exceptions )
+list( APPEND LLVM_CXX_FLAGS -fno-rtti -fno-exceptions )
 
 # Print LLVM variables
 message( "LLVM system libs: ${LLVM_SYSTEM_LIBS}" )