Fix various problems with removal of grammar files when yacc program fails.

Also added VS71COMNTOOLS detection for vc7.


[SVN r18942]

tools/build

@@ -1 +1 @@
-Subproject commit f63161e8c7eed7cf5bd362b8649f90c1d11383f8
+Subproject commit 8f0c4d8f9b167ea0c92158bc67329b88e23e476d