gitignore: replace library catch-all pattern by more specific patterns

Ignoring all files that start with the name of a library matches some
files that are not generated.  So replace libfoo/libfoo* with patterns
for static and shared libraries, pkg-config and version files.

.gitignore

@@ -1,9 +1,14 @@
 .config
 .version
+*.a
 *.o
 *.d
 *.exe
 *.ho
+*.pc
+*.so
+*.so.*
+*.ver
 *-example
 *-test
 config.*
@@ -21,13 +26,7 @@ doc/print_options
 libavcodec/*_tablegen
 libavcodec/*_tables.c
 libavcodec/*_tables.h
-libavcodec/libavcodec*
-libavdevice/libavdevice*
-libavfilter/libavfilter*
-libavformat/libavformat*
 libavutil/avconfig.h
-libavutil/libavutil*
-libswscale/libswscale*
 tests/audiogen
 tests/base64
 tests/data