Default to CAP64 and RISCV architecture

Makefile

@@ -1,11 +1,15 @@
-
-CAP ?= 128
+CAP ?= 64
 ifeq ($(CAP), 128)
 BSCFLAGS = -D CAP128
 else
 BSCFLAGS = -D CAP64
 endif
 
+ARCH ?= RISCV
+ifeq ($(ARCH), RISCV)
+BSCFLAGS += -D RISCV
+endif
+
 verilog-wrappers: CHERICapWrap.bsv CHERICap.bsv CHERICC_Fat.bsv
 	bsc $(BSCFLAGS) -verilog -u $<