gitignore: Use full path instead of relative path to specify patterns

This avoids confusion from patterns meant to only match at the top
level matching files in subdirectories.

.gitignore

-.config
-.version
 *.a
 *.o
 *.d
@@ -14,36 +12,38 @@
 *.ver
 *-example
 *-test
-config.*
-doc/*.1
-doc/*.html
-doc/*.pod
-doxy
-avconv
-avplay
-avprobe
-avserver
-doc/avoptions_codec.texi
-doc/avoptions_format.texi
-doc/print_options
-libavcodec/*_tablegen
-libavcodec/*_tables.c
-libavcodec/*_tables.h
-libavutil/avconfig.h
-tests/audiogen
-tests/base64
-tests/data
-tests/rotozoom
-tests/tiny_psnr
-tests/videogen
-tests/vsynth1
-tools/aviocat
-tools/cws2fws
-tools/graph2dot
-tools/ismindex
-tools/lavfi-showfiltfmts
-tools/pktdumper
-tools/probetest
-tools/qt-faststart
-tools/trasher
-version.h
+/.config
+/.version
+/avconv
+/avplay
+/avprobe
+/avserver
+/config.*
+/version.h
+/doc/*.1
+/doc/*.html
+/doc/*.pod
+/doc/avoptions_codec.texi
+/doc/avoptions_format.texi
+/doc/print_options
+/doxy/
+/libavcodec/*_tablegen
+/libavcodec/*_tables.c
+/libavcodec/*_tables.h
+/libavutil/avconfig.h
+/tests/audiogen
+/tests/base64
+/tests/data/
+/tests/rotozoom
+/tests/tiny_psnr
+/tests/videogen
+/tests/vsynth1/
+/tools/aviocat
+/tools/cws2fws
+/tools/graph2dot
+/tools/ismindex
+/tools/lavfi-showfiltfmts
+/tools/pktdumper
+/tools/probetest
+/tools/qt-faststart
+/tools/trasher