bootstrap: Do not build Ninja generator

The CMake bootstrap process uses Makefile generators so there is no
need to build the Ninja generators during bootstrap.

Source/cmake.cxx

@@ -75,7 +75,9 @@
 # include "cmGlobalWatcomWMakeGenerator.h"
 #endif
 #include "cmGlobalUnixMakefileGenerator3.h"
+#if defined(CMAKE_BUILD_WITH_CMAKE)
 # include "cmGlobalNinjaGenerator.h"
+#endif
 #include "cmExtraCodeLiteGenerator.h"
 
 #if !defined(CMAKE_BOOT_MINGW)
@@ -1857,8 +1859,10 @@ void cmake::AddDefaultGenerators()
 #endif
   this->Generators.push_back(
     cmGlobalUnixMakefileGenerator3::NewFactory());
+#if defined(CMAKE_BUILD_WITH_CMAKE)
   this->Generators.push_back(
     cmGlobalNinjaGenerator::NewFactory());
+#endif
 #if defined(CMAKE_USE_WMAKE)
   this->Generators.push_back(
     cmGlobalWatcomWMakeGenerator::NewFactory());

bootstrap

@@ -322,11 +322,6 @@ CMAKE_CXX_SOURCES="\
   cmExprLexer \
   cmExprParser \
   cmExprParserHelper \
-  cmGlobalNinjaGenerator \
-  cmLocalNinjaGenerator \
-  cmNinjaTargetGenerator \
-  cmNinjaNormalTargetGenerator \
-  cmNinjaUtilityTargetGenerator \
 "
 
 if ${cmake_system_mingw}; then