doxygen: Build Doxygen documentation in the doc/ subdirectory

.gitignore

@@ -28,8 +28,8 @@
 /doc/*.pod
 /doc/avoptions_codec.texi
 /doc/avoptions_format.texi
+/doc/doxy/html/
 /doc/print_options
-/doxy/
 /libavcodec/*_tablegen
 /libavcodec/*_tables.c
 /libavcodec/*_tables.h

Doxyfile

@@ -44,7 +44,7 @@ PROJECT_LOGO           =
 # If a relative path is entered, it will be relative to the location
 # where doxygen was started. If left blank the current directory will be used.
 
-OUTPUT_DIRECTORY       = doxy
+OUTPUT_DIRECTORY       = doc/doxy
 
 # If the CREATE_SUBDIRS tag is set to YES, then doxygen will create
 # 4096 sub-directories (in 2 levels) under the output directory of each output