cmGlobalBorlandMakefileGenerator: Do not inherit from NMake generator

The Borland generator re-implements every method the NMake generator
does, so there is no reason to inherit this way.  Instead inherit
directly from cmGlobalUnixMakefileGenerator3 like all the other
makefile generators do.

Source/cmGlobalBorlandMakefileGenerator.h

@@ -19,7 +19,7 @@
  *
  * cmGlobalBorlandMakefileGenerator manages nmake build process for a tree
  */
-class cmGlobalBorlandMakefileGenerator : public cmGlobalNMakeMakefileGenerator
+class cmGlobalBorlandMakefileGenerator : public cmGlobalUnixMakefileGenerator3
 {
 public:
   cmGlobalBorlandMakefileGenerator();