build: add riscv into host_arch_cc

PR-URL: #39004
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michael Dawson <midawson@redhat.com>

configure.py

@@ -1066,6 +1066,7 @@ def host_arch_cc():
     '__PPC__'     : 'ppc64',
     '__x86_64__'  : 'x64',
     '__s390x__'   : 's390x',
+    '__riscv'     : 'riscv',
   }
 
   rtn = 'ia32' # default
@@ -1078,6 +1079,12 @@ def host_arch_cc():
   if rtn == 'mipsel' and '_LP64' in k:
     rtn = 'mips64el'
 
+  if rtn == 'riscv':
+    if k['__riscv_xlen'] == '64':
+      rtn = 'riscv64'
+    else:
+      rtn = 'riscv32'
+
   return rtn