Mark tests whcih don't work under riscv emulation

Author: tblah

src/libstd/sys/unix/process/process_common.rs

@@ -428,6 +428,7 @@ mod tests {
     // ignored there.
     #[cfg_attr(target_arch = "arm", ignore)]
     #[cfg_attr(target_arch = "aarch64", ignore)]
+    #[cfg_attr(target_arch = "riscv64", ignore)]
     fn test_process_mask() {
         unsafe {
             // Test to make sure that a signal mask does not get inherited.

src/libstd/time.rs

@@ -796,11 +796,11 @@ mod tests {
 
         // Right now for CI this test is run in an emulator, and apparently the
         // aarch64 emulator's sense of time is that we're still living in the
-        // 70s.
+        // 70s. This is also true for riscv (also qemu)
         //
         // Otherwise let's assume that we're all running computers later than
         // 2000.
-        if !cfg!(target_arch = "aarch64") {
+        if !cfg!(target_arch = "aarch64") && !cfg!(target_arch = "riscv64") {
             assert!(a > thirty_years);
         }