Fix one stray {LLVM -> CLANG}_TOOLS_INSTALL_DIR

Follow up to D117977, where I missed this new usage after one rebase.

Thanks @tsteller in https://reviews.llvm.org/D117977#3670919 for
noticing.

Reviewed By: mstorsjo

Differential Revision: https://reviews.llvm.org/D130362

clang/utils/hmaptool/CMakeLists.txt

@@ -1,4 +1,4 @@
-install(PROGRAMS hmaptool DESTINATION "${LLVM_TOOLS_INSTALL_DIR}" COMPONENT hmaptool)
+install(PROGRAMS hmaptool DESTINATION "${CLANG_TOOLS_INSTALL_DIR}" COMPONENT hmaptool)
 add_custom_target(hmaptool ALL DEPENDS "hmaptool")
 set_target_properties(hmaptool PROPERTIES FOLDER "Utils")