Add LLVM libdir to library search path in out-of-tree builds.

This previously was not required because in an out-of-tree build Polly would
only build libraries (LLVMPolly, libPolly, libPollyISL, libPollyPPCG), but no
executables where the libraries would be linked to. This will change when adding
unittests in a follow-up commit.

llvm-svn: 279730

Author: Meinersbur

polly/CMakeLists.txt

@@ -38,6 +38,11 @@ if (NOT DEFINED LLVM_MAIN_SRC_DIR)
     set(${return_var} ${system_libs} PARENT_SCOPE)
   endfunction(get_system_libs)
 
+  execute_process(COMMAND "${LLVM_INSTALL_ROOT}/bin/llvm-config" --libdir
+                  OUTPUT_VARIABLE LLVM_LIBRARY_DIR
+                  OUTPUT_STRIP_TRAILING_WHITESPACE)
+  link_directories("${LLVM_LIBRARY_DIR}")
+
   # Now set the header paths.
   execute_process(COMMAND "${LLVM_INSTALL_ROOT}/bin/llvm-config" --includedir
                   OUTPUT_VARIABLE LLVM_INCLUDE_DIR