Revert "git: Now ignores all files without an extension."

It is not clear why this was required in the first place, and it causes
issues with tools such as `fd` or `rg` that parse .gitignore for
exclusion/inclusion.

Author: mazunki

.gitignore

@@ -1,6 +1,3 @@
-*
-!/**/
-!*.*
 *~
 *.a
 *.o