Fixup .gitignore

Update to match new location of generated crc* code.

Change-Id: I33b62047ff5bca7f5834df0961f3637cb319c80d
diff --git a/.gitignore b/.gitignore
index 9ca9050..df85917 100644
--- a/.gitignore
+++ b/.gitignore
@@ -88,7 +88,7 @@
 doc/*.tag.prep
 tags
 
-src/crc*gen.c
+src/core/crc*gen.c
 src/gsm/gsm0503_conv.c
 src/gsm/*_gen.c
 include/osmocom/core/crc*gen.h