remove stale .gitignore entries

In-tree builds are explicitly disallowed by cmake. Any of these files
showing up in the source tree should be cause for concern.

BUG=aomedia:1254

Change-Id: Iae42c17cbadb6554c6a95bda14daf5ac67e352a7

.gitignore

-*.S
-*.a
-*.asm.s
-*.d
-*.gcda
-*.gcno
-*.o
-*~
-.cproject
-.project
-.settings
-/*-*.mk
-/*.asm
-/*.doxy
-/*.ivf
-/*.ivf.md5
-/.bins
-/.deps
-/.docs
-/.install-*
-/.libs
-/Makefile
-/config.log
-/config.mk
-/docs/
-/doxyfile
-/examples/*.dox
-/examples/decode_to_md5
-/examples/decode_with_drops
-/examples/decode_with_partial_drops
-/examples/example_xma
-/examples/lossless_encoder
-/examples/postproc
-/examples/resize_util
-/examples/set_maps
-/examples/simple_decoder
-/examples/simple_encoder
-/examples/twopass_encoder
-/examples/aom_cx_set_ref
-/examples/av1_spatial_scalable_encoder
-/examples/aom_temporal_scalable_patterns
-/examples/aom_temporal_svc_encoder
-/ivfdec
-/ivfdec.dox
-/ivfenc
-/ivfenc.dox
-/libaom.so*
-/libaom.ver
-/samples.dox
-/test_intra_pred_speed
-/test_libaom
-/aom_api1_migration.dox
-/av1_rtcd.h
-/aom.pc
-/aom_config.c
-/aom_config.h
-/aom_dsp_rtcd.h
-/aom_scale_rtcd.h
-/aom_version.h
-/aomdec
-/aomdec.dox
-/aomenc
-/aomenc.dox
+tags
 TAGS