Add .gdb_history to .gitignore.

Change-Id: I6d5807fe3ec4e11f09c2bb86a45f0883e71d3ed1
Reviewed-on: https://pdfium-review.googlesource.com/33594
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/.gitignore b/.gitignore
index a1b0405..0111ff0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,6 +28,8 @@
 .DS_Store
 .gclient
 .gclient_entries
+.gdb_history
+.gdbinit
 *.aps
 *.filters
 *.opensdf