Revert "ignore changes in submodules when committing everything"

This reverts commit d78ac04ee6.

The benefits of `ignore=all` are that submodules are omitted from
`git status` and `git citool`. The drawbacks are - submodules
are not omitted from `git commit -a` *and* they are omitted
from `git diff` and `git show` output.

As a result one can unintentionally commit changes to submodules and not
see it in the history. Thus drawbacks outweigh benefits here.

.gitmodules

@@ -1,17 +1,13 @@
 [submodule "libmariadb"]
 	path = libmariadb
 	url = https://github.com/MariaDB/mariadb-connector-c.git
-	ignore = all
 [submodule "storage/rocksdb/rocksdb"]
 	path = storage/rocksdb/rocksdb
 	url = https://github.com/facebook/rocksdb.git
-	ignore = all
 [submodule "wsrep-lib"]
 	path = wsrep-lib
 	url = https://github.com/codership/wsrep-lib.git
 	branch = master
-	ignore = all
 [submodule "extra/wolfssl/wolfssl"]
 	path = extra/wolfssl/wolfssl
 	url = https://github.com/wolfSSL/wolfssl.git
-	ignore = all