Update .gitignore to exclude tracked files.

.gitignore was ignoring all the files in the include/bsdiff/ directory
because the path includes "bsdiff". This fixes it to ignore only the
"bsdiff" path on the root directory.

Bug: None
Test: git ls-files -i --exclude-standard
Change-Id: Icc85d8b4b6214786cdf13b3e886e2d7240bbccdb
diff --git a/.gitignore b/.gitignore
index f74437d..d84875d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,11 +4,12 @@
 # any tracked files which get ignored after the change.
 #
 
-# Standard ignores
+# Ignore object files and backup files
 *.o
+*.so
 *~
 
 # Executables
-bsdiff
-bspatch
-unittests
+/bsdiff
+/bspatch
+/bsdiff_unittest