major lifting: get rid of RReg

I've been septic since I introduced it, this commit
proves that it costs more than it helps.  I've also fixed
a bad bug in rega() where I alloc'ed the wrong size for
internal arrays.  Enums now have names so I can use them
to cast in gdb to get the name corresponding to a constant.

lisc/Makefile

@@ -1,7 +1,7 @@
 BIN = lisc
 OBJ = parse.o ssa.o live.o isel.o spill.o rega.o emit.o main.o
 
-CFLAGS = -Wall -Wextra -std=c11 -g -pedantic
+CFLAGS = -Wall -Wextra -std=c99 -g -pedantic
 
 $(BIN): $(OBJ)
 	$(CC) $(LDFLAGS) $(OBJ) -o $@