Fix error leaks, adding SVN_ERR() where appropriate.
Found by: julianfoad
* subversion/libsvn_client/locking_commands.c, subversion/tests/libsvn_repos/repos-test.c, subversion/libsvn_repos/dump.c, subversion/libsvn_repos/commit.c, subversion/svn/util.c, subversion/libsvn_fs_fs/fs_fs.c Add SVN_ERR() wrappers to handle errors returned from called functions.
Per discussion on dev list, revert r18040, re-instating GCC 4.0.1's compilation warnings (which turn into build failures when using -Wall -Werror). The Plan is to add compilation flags (likely -Wno-uninitialized) for GCC which disable this type of warning.