[CMake] Support passing CMAKE_VERBOSE_MAKEFILE through to bootstrap builds.

This option enables full verbosity in recursive CMake builds.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@252523 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -621,6 +621,10 @@ if (CLANG_ENABLE_BOOTSTRAP)
     COMMENT "Clobberring bootstrap build and stamp directories"
     )
 
+  if(CMAKE_VERBOSE_MAKEFILE)
+    set(verbose -DCMAKE_VERBOSE_MAKEFILE=On)
+  endif()
+
   ExternalProject_Add(bootstrap
     DEPENDS clang ${LTO_DEP}
     PREFIX bootstrap
@@ -636,7 +640,7 @@ if (CLANG_ENABLE_BOOTSTRAP)
                 -DCMAKE_CXX_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++
                 -DCMAKE_C_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang
                 -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang
-                ${LTO_LIBRARY} ${LTO_AR} ${LTO_RANLIB}
+                ${LTO_LIBRARY} ${LTO_AR} ${LTO_RANLIB} ${verbose}
     INSTALL_COMMAND ""
     STEP_TARGETS configure build
     ${cmake_3_4_USES_TERMINAL_OPTIONS}