Bug 354448 remove "core" from .gitignore

Add back the mistakenly removed 'core.*' entry for Java core
dump files.

.gitignore

diff --git a/.gitignore b/.gitignore
index e474e81..6563751 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,7 +4,8 @@
 *.bak
 *.patch
 javacore.*
-heapdump.*
+heapdump.*

+core.*

 Snap.*
 target/