[newlib-cygwin] RISC-V: Fix libnosys build.

[Jim Wilson]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=e807c51d784f4bd8acaecbf2441142e60328c1af

commit e807c51d784f4bd8acaecbf2441142e60328c1af
Author: Jim Wilson <jimw@sifive.com>
Date:   Tue Dec 26 12:18:42 2017 -0800

    RISC-V: Fix libnosys build.

Diff:
---
 libgloss/libnosys/configure    | 2 ++
 libgloss/libnosys/configure.in | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/libgloss/libnosys/configure b/libgloss/libnosys/configure
index 046dca5..7c23c7a 100755
--- a/libgloss/libnosys/configure
+++ b/libgloss/libnosys/configure
@@ -2033,6 +2033,8 @@ case "${target}" in
 	;;
   mn10?00-*-*)
 	;;
+  riscv*-*-*)
+	;;
   powerpcle-*-pe)
 	;;
   sh*-*-*)
diff --git a/libgloss/libnosys/configure.in b/libgloss/libnosys/configure.in
index d3d8c89..8908217 100644
--- a/libgloss/libnosys/configure.in
+++ b/libgloss/libnosys/configure.in
@@ -67,6 +67,8 @@ case "${target}" in
 	;;
   mn10?00-*-*)
 	;;
+  riscv*-*-*)
+	;;
   powerpcle-*-pe)
 	;;
   sh*-*-*)