Auto merge of #38650 - infinity0:master, r=alexcrichton

Detect mips CPUs in ./configure

This mirrors existing logic already in src/bootstrap/bootstrap.py

src/test/run-pass/conditional-compile-arch.rs

@@ -22,6 +22,12 @@ pub fn main() { }
 #[cfg(target_arch = "aarch64")]
 pub fn main() { }
 
+#[cfg(target_arch = "mips")]
+pub fn main() { }
+
+#[cfg(target_arch = "mips64")]
+pub fn main() { }
+
 #[cfg(target_arch = "powerpc64")]
 pub fn main() { }