[CMake] Add variables for tracking which runtimes are included

This allows sub-projects to have conditionals based on the presence of other projects.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279172 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Chris Bieneman

runtimes/CMakeLists.txt

@@ -48,6 +48,10 @@ if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
     # The subdirectories need to treat this as standalone builds
     set(${canon_name}_STANDALONE_BUILD On)
 
+    # Setting a variable to let sub-projects detect which other projects
+    # will be included under here.
+    set(HAVE_${canon_name} On)
+
     add_subdirectory(${projName})
   endforeach()