stdint constants in test suite

Passes w/ gcc 11 on Fedora x64.

Protip: So you don;t have to suffer,

```
perl -pe 's/(-?(?:0x)?[A-Fa-f0-9]+)([Uu])?[Ll][Ll]/\U$2INT64_C(\E$1)/mg'
```

tests/core/encoding.c

@@ -14,7 +14,7 @@ void test_core_encoding__decode(void)
 	cl_assert(size == 4);
 
 	buf = (unsigned char *)"\xaa\xaa\xfe\xdc\xbaXY";
-	cl_assert(git_decode_varint(buf, &size) == 1489279344088ULL);
+	cl_assert(git_decode_varint(buf, &size) == UINT64_C(1489279344088));
 	cl_assert(size == 6);
 
 	buf = (unsigned char *)"\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xfe\xdc\xbaXY";
@@ -35,8 +35,8 @@ void test_core_encoding__encode(void)
 	cl_assert(git_encode_varint(buf, 100, 267869656) == 4);
 	cl_assert(!memcmp(buf, "\xfe\xdc\xbaX", 4));
 
-	cl_assert(git_encode_varint(buf, 100, 1489279344088ULL) == 6);
+	cl_assert(git_encode_varint(buf, 100, UINT64_C(1489279344088)) == 6);
 	cl_assert(!memcmp(buf, "\xaa\xaa\xfe\xdc\xbaX", 6));
 
-	cl_assert(git_encode_varint(buf, 1, 1489279344088ULL) == -1);
+	cl_assert(git_encode_varint(buf, 1, UINT64_C(1489279344088)) == -1);
 }

tests/core/strtol.c

@@ -32,7 +32,7 @@ void test_core_strtol__int32(void)
 	assert_l32_parses("  +123 ", 123, 10);
 	assert_l32_parses("  -123 ", -123, 10);
 	assert_l32_parses("  +2147483647 ", 2147483647, 10);
-	assert_l32_parses("  -2147483648 ", -2147483648LL, 10);
+	assert_l32_parses("  -2147483648 ", INT64_C(-2147483648), 10);
 	assert_l32_parses("A", 10, 16);
 	assert_l32_parses("1x1", 1, 10);
 
@@ -49,9 +49,9 @@ void test_core_strtol__int64(void)
 	assert_l64_parses("  +123 ", 123, 10);
 	assert_l64_parses("  -123 ", -123, 10);
 	assert_l64_parses("  +2147483647 ", 2147483647, 10);
-	assert_l64_parses("  -2147483648 ", -2147483648LL, 10);
-	assert_l64_parses("  2147483657 ", 2147483657LL, 10);
-	assert_l64_parses("  -2147483657 ", -2147483657LL, 10);
+	assert_l64_parses("  -2147483648 ", INT64_C(-2147483648), 10);
+	assert_l64_parses("  2147483657 ", INT64_C(2147483657), 10);
+	assert_l64_parses("  -2147483657 ", INT64_C(-2147483657), 10);
 	assert_l64_parses(" 9223372036854775807  ", INT64_MAX, 10);
 	assert_l64_parses("   -9223372036854775808  ", INT64_MIN, 10);
 	assert_l64_parses("   0x7fffffffffffffff  ", INT64_MAX, 16);

tests/graph/commit_graph.c

@@ -23,14 +23,14 @@ void test_graph_commit_graph__parse(void)
 	cl_git_pass(git_oid_fromstr(&id, "418382dff1ffb8bdfba833f4d8bbcde58b1e7f47"));
 	cl_assert_equal_oid(&e.tree_oid, &id);
 	cl_assert_equal_i(e.generation, 1);
-	cl_assert_equal_i(e.commit_time, 1273610423ull);
+	cl_assert_equal_i(e.commit_time, UINT64_C(1273610423));
 	cl_assert_equal_i(e.parent_count, 0);
 
 	cl_git_pass(git_oid_fromstr(&id, "be3563ae3f795b2b4353bcce3a527ad0a4f7f644"));
 	cl_git_pass(git_commit_graph_entry_find(&e, cgraph, &id, GIT_OID_HEXSZ));
 	cl_assert_equal_oid(&e.sha1, &id);
 	cl_assert_equal_i(e.generation, 5);
-	cl_assert_equal_i(e.commit_time, 1274813907ull);
+	cl_assert_equal_i(e.commit_time, UINT64_C(1274813907));
 	cl_assert_equal_i(e.parent_count, 2);
 
 	cl_git_pass(git_oid_fromstr(&id, "9fd738e8f7967c078dceed8190330fc8648ee56a"));
@@ -66,7 +66,7 @@ void test_graph_commit_graph__parse_octopus_merge(void)
 	cl_git_pass(git_oid_fromstr(&id, "348f16ffaeb73f319a75cec5b16a0a47d2d5e27c"));
 	cl_assert_equal_oid(&e.tree_oid, &id);
 	cl_assert_equal_i(e.generation, 7);
-	cl_assert_equal_i(e.commit_time, 1447083009ull);
+	cl_assert_equal_i(e.commit_time, INT64_C(1447083009));
 	cl_assert_equal_i(e.parent_count, 3);
 
 	cl_git_pass(git_oid_fromstr(&id, "ad2ace9e15f66b3d1138922e6ffdc3ea3f967fa6"));

tests/revwalk/basic.c

@@ -530,7 +530,7 @@ void test_revwalk_basic__big_timestamp(void)
 	cl_git_pass(git_reference_peel((git_object **) &tip, head, GIT_OBJECT_COMMIT));
 
 	/* Commit with a far-ahead timestamp, we should be able to parse it in the revwalk */
-	cl_git_pass(git_signature_new(&sig, "Joe", "joe@example.com", 2399662595ll, 0));
+	cl_git_pass(git_signature_new(&sig, "Joe", "joe@example.com", INT64_C(2399662595), 0));
 	cl_git_pass(git_commit_tree(&tree, tip));
 
 	cl_git_pass(git_commit_create(&id, _repo, "HEAD", sig, sig, NULL, "some message", tree, 1,