Rename core.abbrevlength back to core.abbrev

It corresponds to --abbrev=$n command line option after all.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -567,7 +567,7 @@ core.sparseCheckout::
 	Enable "sparse checkout" feature. See section "Sparse checkout" in
 	linkgit:git-read-tree[1] for more information.
 
-core.abbrevLength::
+core.abbrev::
 	Set the length object names are abbreviated to.  If unspecified,
 	many commands abbreviate to 7 hexdigits, which may not be enough
 	for abbreviated object names to stay unique for sufficiently long

config.c

@@ -531,7 +531,7 @@ static int git_default_core_config(const char *var, const char *value)
 		return 0;
 	}
 
-	if (!strcmp(var, "core.abbrevlength")) {
+	if (!strcmp(var, "core.abbrev")) {
 		int abbrev = git_config_int(var, value);
 		if (abbrev < minimum_abbrev || abbrev > 40)
 			return -1;