[CMake] Create tool header collector target only when building tools

`HeaderDependencies.cpp` cannot be compiled with
`SWIFT_INCLUDE_TOOLS=OFF` because it depends on `Config.h` which is only
generated while building tools. Exclude it from the build to fix `all`
target.

Follow-up to b39dba3

Author: kateinoigakukun

include/CMakeLists.txt

@@ -1,30 +1 @@
 add_subdirectory(swift)
-
-
-# Create a library that depends on all headers defined in include/swift/module.modulemap
-#
-# TODO: generate this dynamically through the modulemap; this cannot use `sed`
-# as that is not available on all platforms (e.g. Windows).
-file(GENERATE
-  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp"
-  CONTENT "
-#define COMPILED_WITH_SWIFT
-#define SWIFT_TARGET
-
-#include \"swift/Basic/BasicBridging.h\"
-#include \"swift/AST/ASTBridging.h\"
-#include \"swift/IDE/IDEBridging.h\"
-#include \"swift/Parse/ParseBridging.h\"
-#include \"swift/SIL/SILBridging.h\"
-#include \"swift/SILOptimizer/OptimizerBridging.h\"
-")
-add_library(importedHeaderDependencies "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp")
-
-# When building unified, we need to make sure all the Clang headers are
-# generated before we try to use them.
-# When building Swift against an already compiled LLVM/Clang, like
-# build-script does, this target does not exist, but the headers
-# are already completely generated at that point.
-if(TARGET clang-tablegen-targets)
-  add_dependencies(importedHeaderDependencies clang-tablegen-targets)
-endif()

lib/CMakeLists.txt

@@ -76,6 +76,34 @@ if (SWIFT_BUILD_SWIFT_SYNTAX)
          EXPORT_LINK_INTERFACE_LIBRARIES)
 endif()
 
+# Create a library that depends on all tool headers defined in include/module.modulemap
+#
+# TODO: generate this dynamically through the modulemap; this cannot use `sed`
+# as that is not available on all platforms (e.g. Windows).
+file(GENERATE
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp"
+  CONTENT "
+#define COMPILED_WITH_SWIFT
+#define SWIFT_TARGET
+
+#include \"swift/Basic/BasicBridging.h\"
+#include \"swift/AST/ASTBridging.h\"
+#include \"swift/IDE/IDEBridging.h\"
+#include \"swift/Parse/ParseBridging.h\"
+#include \"swift/SIL/SILBridging.h\"
+#include \"swift/SILOptimizer/OptimizerBridging.h\"
+")
+add_library(importedHeaderDependencies "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp")
+
+# When building unified, we need to make sure all the Clang headers are
+# generated before we try to use them.
+# When building Swift against an already compiled LLVM/Clang, like
+# build-script does, this target does not exist, but the headers
+# are already completely generated at that point.
+if(TARGET clang-tablegen-targets)
+  add_dependencies(importedHeaderDependencies clang-tablegen-targets)
+endif()
+
 add_subdirectory(APIDigester)
 add_subdirectory(AST)
 add_subdirectory(ASTGen)