test: ensure 64 bit, test .plt/.rela.plt searching

Test parsing .plt and .rela.plt from the dynamic segment.

For this we should make sure our binaries are compiled as 64
bit as a 32 bit binary will not have a .rela.plt but a
.rel.plt section instead.

test/test_files/Makefile

 CC=gcc
-SHARED_FLAGS=-shared -fPIC -O3
+SHARED_FLAGS=-shared -fPIC -O3 -m64
 CFLAGS=$(SHARED_FLAGS) -Wl,-Bsymbolic-functions
 RPATH_DIR=rpath_dir
 RPATH_SUBDIR=$(RPATH_DIR)/rpath_subdir

test/test_library.py

@@ -425,5 +425,17 @@ class TestLibrary(unittest.TestCase):
         self.assertIn(binary.fullname, lib.get_users_by_name('external_caller'))
         self.assertIn(binary.fullname, lib.get_users_by_name('second_level_caller'))
 
+    def test_7_search_for_plt(self):
+        _, library = create_store_and_lib(TEST_LIBRARY)
+        searched_plt = library._search_for_plt()
+        section_plt = library._elffile.get_section_by_name('.plt')
+        self.assertEquals(searched_plt['sh_offset'], section_plt['sh_offset'])
+
+    def test_7_dynamic_rela_plt(self):
+        _, library = create_store_and_lib(TEST_LIBRARY)
+        searched_plt = library._create_mock_rela_plt()
+        section_plt = library._elffile.get_section_by_name('.rela.plt')
+        self.assertEquals(searched_plt['sh_offset'], section_plt['sh_offset'])
+
 if __name__ == '__main__':
     unittest.main()