!32 Fix build error on riscv64

From: @misaka00251 
Reviewed-by: @Charlie_li 
Signed-off-by: @Charlie_li

mpich.spec

@@ -1,7 +1,7 @@
 Summary:        A high-performance implementation of MPI
 Name:           mpich
 Version:        4.0.3
-Release:        3
+Release:        4
 License:        MIT
 URL:            http://www.mpich.org/
 Source0:        http://www.mpich.org/static/downloads/%{version}/mpich-%{version}.tar.gz
@@ -66,7 +66,7 @@ mpich support for Python 3.
 %{!?opt_fc_fflags: %global opt_fc_fflags %{optflags}}
 %{!?opt_f77_fflags: %global opt_f77_fflags %{optflags}}
 
-%ifarch aarch64 loongarch64
+%ifarch aarch64 loongarch64 riscv64
 %global m_option ""
 %else
 %global m_option -m64
@@ -201,6 +201,9 @@ make check V=1
 %{python3_sitearch}/mpich.pth
 
 %changelog
+* Thu Jul 27 2023 misaka00251 <liuxin@iscas.ac.cn> - 4.0.3-4
+- Fix build error on riscv64
+
 * Tue May 23 2023 huajingyun <huajingyun@loongson.cn> - 4.0.3-3
 - Fix build error on loongarch64