Add test for patching a system call instruction

makefile

 CFLAGS = -g -O0 -Wall -Werror -Wextra -Wno-missing-field-initializers         \
          -Wno-unused-parameter -I.
 LDFLAGS = -g
 CPPFLAGS =
 DEPFLAGS = -MMD -MF $@.d
 MODS := allocator preload library debug maps x86_decode securemem sandbox     \
         syscall_entrypoint system_call_table                                  \
         trusted_thread trusted_thread_asm trusted_process                     \
         access exit fault_handler_asm clone                                   \
         getpid gettid ioctl ipc madvise mmap mprotect                         \
         munmap open prctl reference_trusted_thread sigaction sigprocmask      \
         socketcall stat tls_setup tls_setup_helper
 TEST_MODS := \
         tests/clone_test_helper \
         tests/test_runner \
+        tests/test_patching \
+        tests/test_patching_input \
         tests/test_syscalls
 OBJS64 := $(shell echo ${MODS} | xargs -n 1 | sed -e 's/$$/.o64/')
 OBJS32 := $(shell echo ${MODS} | xargs -n 1 | sed -e 's/$$/.o32/')
 TEST_OBJS64 := $(shell echo ${TEST_MODS} | xargs -n 1 | sed -e 's/$$/.o64/')
 TEST_OBJS32 := $(shell echo ${TEST_MODS} | xargs -n 1 | sed -e 's/$$/.o32/')
 ALL_OBJS = $(OBJS32) $(OBJS64) \
            $(TEST_OBJS32) $(TEST_OBJS64) \
            timestats.o playground.o
 DEP_FILES = $(wildcard $(foreach f,$(ALL_OBJS),$(f).d))
 
@@ skipping 90 matching lines @@
 
 .cc.o32:
         ${CXX} ${CFLAGS} ${CPPFLAGS} ${DEPFLAGS} -m32 -fPIC -c -o $@ $<
 
 .c.o32:
         ${CC} ${CFLAGS} ${CPPFLAGS} ${DEPFLAGS} -m32 --std=gnu99 -fPIC \
                 -c -o $@ $<
 
 .S.o32:
         ${CC} ${CFLAGS} ${CPPFLAGS} ${DEPFLAGS} -m32 -c -o $@ $<