Define UNWIND_DATA_REG for loongarch64

Author: zhaixiaojuan

Diff for: library/std/src/personality/gcc.rs

@@ -77,6 +77,9 @@ const UNWIND_DATA_REG: (i32, i32) = (0, 1); // R0, R1
 #[cfg(any(target_arch = "riscv64", target_arch = "riscv32"))]
 const UNWIND_DATA_REG: (i32, i32) = (10, 11); // x10, x11
 
+#[cfg(target_arch = "loongarch64")]
+const UNWIND_DATA_REG: (i32, i32) = (4, 5); // a0, a1
+
 // The following code is based on GCC's C and C++ personality routines.  For reference, see:
 // https://github.com/gcc-mirror/gcc/blob/master/libstdc++-v3/libsupc++/eh_personality.cc
 // https://github.com/gcc-mirror/gcc/blob/trunk/libgcc/unwind-c.c