.gitignore: Ignore .cache directory & compile_commands.json

To configure the clangd plugin for various editors, The command
'bear -- make' is used to generate the compile_commands.json.

The clangd plugin creates a .cache directory under inside coreboot.

Just ignore both of these.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: Ic844f807ab48597b8aae29bb64ab16d6c8dff217
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65320
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

.gitignore

@@ -31,6 +31,8 @@ site-local
 # Development friendly files
 tags
 .clang_complete
+.cache
+compile_commands.json
 
 # Cross-compile toolkits
 xgcc/