linux.cf: always use bison

For some reason, whenever OSMajorVersion was >= 2 (this equates to a
2.x kernel or above), yacc would be used instead of bison.

On Ubuntu, and probably other linux systems, yacc is just a shell
wrapper around bison, so let's just use that directly.

cde/config/cf/linux.cf

@@ -120,11 +120,7 @@ XCOMM binutils:  (LinuxBinUtilsMajorVersion)
 
 #define MkdirHierCmd		mkdir -p
 #define CppCmd			/lib/cpp
-#if OSMajorVersion >= 2
-# define YaccCmd                yacc
-#else
-# define YaccCmd                bison -y
-#endif
+#define YaccCmd                bison -y
 #define LexCmd			flex -l
 #define LexLib			-lfl
 #define PreProcessCmd		CcCmd -E