Revert "riscv32-nemu: add integer library functions to pass linking"

This reverts commit aca9a5dd6d.

am/arch/platform/nemu.mk

@@ -18,7 +18,7 @@ NEMU_ARGS = -b $(MAINARGS) -l $(shell dirname $(BINARY))/nemu-log.txt $(BINARY).
 
 image:
 	@echo + LD "->" $(BINARY_REL).elf
-	@$(LD) $(LDFLAGS) --gc-sections -T $(LD_SCRIPT) -e _start -o $(BINARY).elf --start-group $(LINK_FILES) --end-group
+	@$(LD) $(LDFLAGS) --gc-sections -T $(LD_SCRIPT) -e _start -o $(BINARY).elf $(LINK_FILES)
 	@$(OBJDUMP) -d $(BINARY).elf > $(BINARY).txt
 	@echo + OBJCOPY "->" $(BINARY_REL).bin
 	@$(OBJCOPY) -S --set-section-flags .bss=alloc,contents -O binary $(BINARY).elf $(BINARY).bin

am/arch/riscv32-nemu.mk

@@ -1,4 +1,2 @@
 include $(AM_HOME)/am/arch/isa/riscv32.mk
 include $(AM_HOME)/am/arch/platform/nemu.mk
-
-AM_SRCS += riscv32/nemu/libint.c

am/src/riscv32/nemu/libint.c

@@ -1,14 +0,0 @@
-#include <klib.h>
-
-// for more details, refer to
-// https://gcc.gnu.org/onlinedocs/gccint/Integer-library-routines.html
-
-// only use for linking
-
-int __clzsi2 (unsigned int a) {
-  assert(0);
-}
-
-int __ctzsi2 (unsigned int a) {
-  assert(0);
-}