Allow each toolset to accept multielement command. Each element will be

individually quoted, and check-for-existance will be applied only to
the first element.


[SVN r23246]

tools/build

@@ -1 +1 @@
-Subproject commit 07188495957d6ada793b5669cbc63ad771fc38b6
+Subproject commit 5626978bc25825840799dff8dbf326526dc0df23