Remove the "invalid" stacking rule.

When ncg fell back on this rule, it did emit the string "invalid" in
the assembly code and caused a syntax error in the assembler.

Adjust the stacking rules so we can stack LOCAL, CONST, and LABEL
without falling back on the "invalid" rule, and so we can stack them
when we have no free register except the scratch register.

mach/powerpc/ncg/table

@@ -233,7 +233,6 @@ TOKENS
 
 SETS
 
-	TOKEN              = LABEL + CONST + LOCAL.
 	GPRI               = GPR + GPRE.
 	
 	SUM_ALL            = SUM_RC + SUM_RR.
@@ -348,8 +347,7 @@ INSTRUCTIONS
   gpr_ro_gpr_gpr  GPRI:ro, GPRI:ro, GPRI:ro.
   gpr_wo_gprindirect GPRI:wo, GPRINDIRECT:ro.
   gpr_wo_gpr_gpr  GPRI:wo, GPRI:ro, GPRI:ro.
-  
+
-  invalid "invalid".
   comment "!" LABEL+LABELI:ro.
 
 
@@ -753,25 +751,28 @@ TESTS
 
 
 STACKINGRULES
-	
+
+	from LOCAL to STACK
+		gen
+			COMMENT("stack LOCAL")
+			stwu {GPRE, regvar(%1.off)}, {GPRINDIRECT, SP, 0-4}
+
 	from GPR to STACK
 		gen
 			COMMENT("stack GPR")
 			stwu %1, {GPRINDIRECT, SP, 0-4}
 	
 	from CONST to STACK
-		uses REG
 		gen
 			COMMENT("stack CONST")
-			move %1, %a
+			move %1, SCRATCH
-			stwu %a, {GPRINDIRECT, SP, 0-4}
+			stwu SCRATCH, {GPRINDIRECT, SP, 0-4}
 			
 	from LABEL to STACK
-		uses REG
 		gen
 			COMMENT("stack LABEL")
-			move %1, {GPRE, %a}
+			move %1, SCRATCH
-			stwu %a, {GPRINDIRECT, SP, 0-4}
+			stwu SCRATCH, {GPRINDIRECT, SP, 0-4}
 			
 	from SEX_B to STACK
 		gen
@@ -809,13 +810,9 @@ STACKINGRULES
 		gen
 			COMMENT("stack FSREG")
 			stfsu %1, {GPRINDIRECT, SP, 0-4}
-			
+
-	from TOKEN to STACK
+
-		gen
+
-			invalid.
-			
-		
-		
 COERCIONS
 
 	from REG