[runtimes] Add umbrella targets for runtimes

[smeenai]

Summary

This will create e.g. a compiler-rt target that'll build compiler-rt for
all configured targets, similar to how the runtimes umbrella target
builds all the runtimes for all configured targets.

[compnerd]

Sure, seems reasonable.

llvm/runtimes/CMakeLists.txt

else()
         add_custom_target(runtimes-configure)
         add_custom_target(install-runtimes)
         add_custom_target(install-runtimes-stripped)
         if(LLVM_INCLUDE_TESTS)
           add_custom_target(check-runtimes)
           add_custom_target(runtimes-test-depends)
           set(test_targets "")
         endif()
+        foreach(runtime_name ${runtime_names})
+          add_custom_target(${runtime_name})
+          add_custom_target(install-${runtime_name})
+          add_custom_target(install-${runtime_name}-stripped)
+        endforeach()
         if(LLVM_RUNTIME_DISTRIBUTION_COMPONENTS)
           foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
             add_custom_target(${component})
             add_custom_target(install-${component})
             add_custom_target(install-${component}-stripped)
           endforeach()
         endif()
       endif()
 
       foreach(name ${LLVM_RUNTIME_TARGETS})
         runtime_register_target(${name} ${name}
           DEPENDS ${deps})
 
         add_dependencies(runtimes runtimes-${name})
         add_dependencies(runtimes-configure runtimes-${name}-configure)
         add_dependencies(install-runtimes install-runtimes-${name})
         add_dependencies(install-runtimes-stripped install-runtimes-${name}-stripped)
         if(LLVM_INCLUDE_TESTS)
           add_dependencies(check-runtimes check-runtimes-${name})
           add_dependencies(runtimes-test-depends runtimes-test-depends-${name})
         endif()
+        foreach(runtime_name ${runtime_names})
+          add_dependencies(${runtime_name} ${runtime_name}-${name})
+          add_dependencies(install-${runtime_name} install-${runtime_name}-${name})
+          add_dependencies(install-${runtime_name}-stripped install-${runtime_name}-${name}-stripped)
+        endforeach()
       endforeach()
 
       foreach(multilib ${LLVM_RUNTIME_MULTILIBS})
         foreach(name ${LLVM_RUNTIME_MULTILIB_${multilib}_TARGETS})
           runtime_register_target(${name}+${multilib} ${name}
             DEPENDS runtimes-${name}
             CMAKE_ARGS -DLLVM_RUNTIMES_PREFIX=${name}/
                        -DLLVM_RUNTIMES_LIBDIR_SUBDIR=${multilib})
           add_dependencies(runtimes runtimes-${name}+${multilib})
           add_dependencies(runtimes-configure runtimes-${name}+${multilib}-configure)
           add_dependencies(install-runtimes install-runtimes-${name}+${multilib})
           add_dependencies(install-runtimes-stripped install-runtimes-${name}+${multilib}-stripped)
+          foreach(runtime_name ${runtime_names})
+            add_dependencies(${runtime_name} ${runtime_name}-${name}+${multilib})
+            add_dependencies(install-${runtime_name} install-${runtime_name}-${name}+${multilib})
+            add_dependencies(install-${runtime_name}-stripped install-${runtime_name}-${name}+${multilib}-stripped)
+          endforeach()
         endforeach()
       endforeach()
     endif()
 
     if(NOT LLVM_BUILD_INSTRUMENTED AND CLANG_ENABLE_BOOTSTRAP)
       # TODO: This is a hack needed because the libcxx headers are copied into the
       # build directory during configuration. Without that step the clang in the
       # build directory cannot find the C++ headers in certain configurations.