Add support for `getrandom`.

And a simple test.

Bug: linux-syscall-support:31
Change-Id: I994549c5d1eae028cad41496387d763eb00adddf
Reviewed-on: https://chromium-review.googlesource.com/c/linux-syscall-support/+/2209720
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/linux_syscall_support.h b/linux_syscall_support.h
index a087903..e5bc63e 100644
--- a/linux_syscall_support.h
+++ b/linux_syscall_support.h
@@ -954,6 +954,9 @@
 #ifndef __NR_fallocate
 #define __NR_fallocate          324
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          355
+#endif
 /* End of i386 definitions                                                   */
 #elif defined(__ARM_ARCH_3__) || defined(__ARM_EABI__)
 #ifndef __NR_setresuid
@@ -1058,6 +1061,9 @@
 #ifndef __NR_getcpu
 #define __NR_getcpu             (__NR_SYSCALL_BASE + 345)
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          (__NR_SYSCALL_BASE + 384)
+#endif
 /* End of ARM 3/EABI definitions                                             */
 #elif defined(__aarch64__)
 #ifndef __NR_setxattr
@@ -1155,6 +1161,9 @@
 #ifndef __NR_move_pages
 #define __NR_move_pages         239
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          278
+#endif
 /* End of aarch64 definitions                                                */
 #elif defined(__x86_64__)
 #ifndef __NR_pread64
@@ -1246,6 +1255,9 @@
 #ifndef __NR_fallocate
 #define __NR_fallocate          285
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          318
+#endif
 /* End of x86-64 definitions                                                 */
 #elif defined(__mips__)
 #if _MIPS_SIM == _MIPS_SIM_ABI32
@@ -1347,6 +1359,9 @@
 #ifndef __NR_ioprio_get
 #define __NR_ioprio_get         (__NR_Linux + 315)
 #endif
+#ifndef __NR_getrandom
+#define __NR_getrandom          (__NR_Linux + 353)
+#endif
 /* End of MIPS (old 32bit API) definitions */
 #elif  _MIPS_SIM == _MIPS_SIM_ABI64
 #ifndef __NR_pread64
@@ -1425,6 +1440,9 @@
 #ifndef __NR_ioprio_get
 #define __NR_ioprio_get         (__NR_Linux + 274)
 #endif
+#ifndef __NT_getrandom
+#define                         (__NR_Linux + 313)
+#endif
 /* End of MIPS (64bit API) definitions */
 #else
 #ifndef __NR_setresuid
@@ -3658,6 +3676,12 @@
                          int, f, int, mode, loff_t, offset, loff_t, len)
     #endif
   #endif
+  #if defined(__NR_getrandom)
+    LSS_INLINE ssize_t LSS_NAME(getrandom)(void* buffer, size_t length,
+                                           unsigned int flags) {
+      LSS_BODY(3, ssize_t, getrandom, buffer, length, flags);
+    }
+  #endif
   #if defined(__NR_newfstatat)
     LSS_INLINE _syscall4(int, newfstatat,         int,   d,
                          const char *,            p,