re PR go/84484 (libgo configure tests fail to find -latomic)

	PR go/84484
    libgo: add support for riscv64
    
    Patch by Andreas Schwab.
    
    Reviewed-on: https://go-review.googlesource.com/96377

	* go.test/go-test.exp (go-set-goarch): Recognize riscv64-*-*.

From-SVN: r257914
diff --git a/libgo/configure.ac b/libgo/configure.ac
index 1f49aee..eabe294 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -224,10 +224,10 @@
 #   - libgo/go/syscall/endian_XX.go
 #   - possibly others
 # - possibly update files in libgo/go/internal/syscall/unix
-ALLGOARCH="386 alpha amd64 amd64p32 arm armbe arm64 arm64be ia64 m68k mips mipsle mips64 mips64le mips64p32 mips64p32le ppc ppc64 ppc64le s390 s390x sh shbe sparc sparc64"
+ALLGOARCH="386 alpha amd64 amd64p32 arm armbe arm64 arm64be ia64 m68k mips mipsle mips64 mips64le mips64p32 mips64p32le ppc ppc64 ppc64le riscv64 s390 s390x sh shbe sparc sparc64"
 
 # All known GOARCH family values.
-ALLGOARCHFAMILY="I386 ALPHA AMD64 ARM ARM64 IA64 M68K MIPS MIPS64 PPC PPC64 S390 S390X SH SPARC SPARC64"
+ALLGOARCHFAMILY="I386 ALPHA AMD64 ARM ARM64 IA64 M68K MIPS MIPS64 PPC PPC64 RISCV64 S390 S390X SH SPARC SPARC64"
 
 GOARCH=unknown
 case ${host} in
@@ -304,6 +304,9 @@
 [GOARCH=ppc64le],
 [GOARCH=ppc64])])
     ;;
+  riscv64-*-*)
+    GOARCH=riscv64
+    ;;
   s390*-*-*)
     AC_COMPILE_IFELSE([
 #if defined(__s390x__)