configure: Accept version suffix in solaris name

Summary: OpenIndiana apparently reports a triple of i386-pc-solaris2.11.

Reviewers: hvr

Subscribers: rwbarton, thomie, erikd, carter

Differential Revision: https://phabricator.haskell.org/D4487

(cherry picked from commit 4fa077a2a1d6e6e7a45ef03a1075ff3c7dddb23d)

aclocal.m4

@@ -1869,6 +1869,9 @@ case "$1" in
   mips*)
     $2="mips"
     ;;
+  nios2)
+    $2="nios2"
+    ;;
   powerpc64le*)
     $2="powerpc64le"
     ;;