Add riscv32 support for musl C library based linux platforms

src/unix/linux_like/linux/musl/b32/mod.rs

@@ -60,6 +60,9 @@ cfg_if! {
     } else if #[cfg(any(target_arch = "hexagon"))] {
         mod hexagon;
         pub use self::hexagon::*;
+    } else if #[cfg(any(target_arch = "riscv32"))] {
+        mod riscv32;
+        pub use self::riscv32::*;
     } else {
         // Unknown target_arch
     }

src/unix/linux_like/linux/musl/b32/riscv32/align.rs

@@ -0,0 +1,7 @@
+s_no_extra_traits! {
+    #[allow(missing_debug_implementations)]
+    #[repr(align(8))]
+    pub struct max_align_t {
+        priv_: (i64, f64)
+    }
+}