Adding git ignore file.

BUG=
TEST=

Review URL: http://webrtc-codereview.appspot.com/173001

git-svn-id: http://webrtc.googlecode.com/svn/trunk@638 4adac7df-926f-26a2-2b94-8c16560cd09d

.gitignore

@@ -0,0 +1,49 @@
+*.mk
+*.Makefile
+*.ncb
+*.ninja
+*.props
+*.pyc
+*.rules
+*.scons
+*.sdf
+*.sln
+*.suo
+*.targets
+*.user
+*.vcproj
+*.vcxproj
+*.vcxproj.filters
+*.vpj
+*.vpw
+*.vpwhistu
+*.vtg
+*.xcodeproj
+*~
+.*.sw?
+.DS_Store
+.cproject
+.gdb_history
+.gdbinit
+.metadata
+.project
+.settings
+/build
+/gyp-mac-tool
+/Makefile
+/out
+/src/supplement.gypi
+/testFiles
+/testing
+/third_party/expat
+/third_party/google-gflags/src
+/third_party/jsoncpp
+/third_party/libjingle
+/third_party/libjpeg
+/third_party/libjpeg_turbo
+/third_party/libvpx
+/third_party/protobuf
+/third_party/yasm
+/tools/gyp
+/x86-generic_out/
+/xcodebuild