tests: Test CPU-based RNG on all x86 targets

This allows us to verify the RDRAND implementation on Linux.

Signed-off-by: Joe Richey <joerichey@google.com>

src/lib.rs

@@ -217,3 +217,5 @@ pub fn getrandom(dest: &mut [u8]) -> Result<(), Error> {
 
 #[cfg(test)]
 mod test_common;
+#[cfg(test)]
+mod test_cpu;

src/test_cpu.rs

@@ -0,0 +1,8 @@
+// We only test the CPU-based RNG source on supported architectures.
+#![cfg(target_arch = "x86_64")]
+
+#[path = "rdrand.rs"]
+mod rdrand;
+use rdrand::getrandom_inner as getrandom;
+#[path = "test_common.rs"]
+mod test_common;