FindProtobuf: Fix protobuf_generate_*() to handle subdirs

The change in commit v3.7.0-rc1~513^2 (FindProtobuf: fix
protobuf_generate_*() to handle proto files in subdirs, 2016-06-09)
incorrectly adds subdirectories to the path of the generated files when
`*.proto` files are passed to `protobuf_generate_*` with subdirectories.
This behavior is not correct when `PROTOBUF_GENERATE_CPP_APPEND_PATH` is
True (default behavior) as `protoc` will generate output file in the
current build directory.

Modules/FindProtobuf.cmake

@@ -136,9 +136,11 @@ function(PROTOBUF_GENERATE_CPP SRCS HDRS)
   foreach(FIL ${ARGN})
     get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
     get_filename_component(FIL_WE ${FIL} NAME_WE)
-    get_filename_component(FIL_DIR ${FIL} DIRECTORY)
-    if(FIL_DIR)
-      set(FIL_WE "${FIL_DIR}/${FIL_WE}")
+    if(NOT PROTOBUF_GENERATE_CPP_APPEND_PATH)
+      get_filename_component(FIL_DIR ${FIL} DIRECTORY)
+      if(FIL_DIR)
+        set(FIL_WE "${FIL_DIR}/${FIL_WE}")
+      endif()
     endif()
 
     list(APPEND ${SRCS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.pb.cc")
@@ -197,9 +199,11 @@ function(PROTOBUF_GENERATE_PYTHON SRCS)
   foreach(FIL ${ARGN})
     get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
     get_filename_component(FIL_WE ${FIL} NAME_WE)
-    get_filename_component(FIL_DIR ${FIL} DIRECTORY)
-    if(FIL_DIR)
-      set(FIL_WE "${FIL_DIR}/${FIL_WE}")
+    if(NOT PROTOBUF_GENERATE_CPP_APPEND_PATH)
+      get_filename_component(FIL_DIR ${FIL} DIRECTORY)
+      if(FIL_DIR)
+        set(FIL_WE "${FIL_DIR}/${FIL_WE}")
+      endif()
     endif()
 
     list(APPEND ${SRCS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}_pb2.py")