Reboot when running program with two .c files

I wrote a very simple test program that runs just fine:

int main(int argc, char *argv)
{
  unsigned char *p = (unsigned char *) malloc(2048*sizeof(unsigned char));
  printf("Allocation via malloc() succeeded\n");
  free(p);
}

extern void foo(void);
int main(int argc, char *argv)
{
  foo();
}

#include <unistd.h># include <stdlib.h># include <stdio.h>
void foo()
{
  unsigned char *p = (unsigned char *) malloc(2048*sizeof(unsigned char));
  printf("Allocation via malloc() succeeded\n");
  free(p);
}

include ../Rules.mak
VERSION=$(shell cat ../../VERSION)
CFLAGS += $(INCLUDES) -O2 -nostdinc -Wall -DLINUX -g
SRC = test_malloc.c foo.c
OBJ = $(addsuffix .o, $(basename $(SRC)))
LIBDIRS += -L/cygdrive/c/Altera/kits/nios2_51/bin/eclipse/plugins/com.microtronix.nios2linux.uClibc_1.4.0/lib
LDFLAGS += -elf2flt
LIBS += -lc
all: test_malloc.exe
test_malloc.exe: $(OBJ) Makefile#        $(CC) -o $@ $(OBJ) $(LIBDIRS) $(LIBS)#        $(CC) $(CFLAGS) $< -o $@
install: all
        cp test_malloc.exe /cygdrive/c/opt/toga/linux_root/home/
clean:
        rm -f test_malloc.exe $(OBJ)
.PHONY: all install uninstall clean