Add rlim64_t to libc/include/sys/resource

crosvm is using rlim64_t. Adding for portability.

Bug: 255594691
Test: m libc && m bionic
Change-Id: I752bfdaa23d900278fe7224306d785b0c9f67d3f
diff --git a/tests/sys_resource_test.cpp b/tests/sys_resource_test.cpp
index 0247fcb..492fabd 100644
--- a/tests/sys_resource_test.cpp
+++ b/tests/sys_resource_test.cpp
@@ -26,6 +26,7 @@
   ASSERT_NE(sizeof(rlimit), sizeof(rlimit64));
   ASSERT_EQ(4U, sizeof(rlim_t));
 #endif
+  ASSERT_EQ(8U, sizeof(rlim64_t));
 }
 
 class SysResourceTest : public ::testing::Test {