We now need alex >= 2.0.1

aclocal.m4

@@ -258,8 +258,7 @@ dnl do without it for now.
 
 dnl
 dnl Check for Alex and version.  If we're building GHC, then we need
-dnl at least Alex version 2.0.  If there's no installed Alex, we look
-dnl for a alex source tree and point the build system at that instead.
+dnl at least Alex version 2.0.1.
 dnl
 AC_DEFUN([FPTOOLS_ALEX],
 [
@@ -276,8 +275,8 @@ changequote([, ])dnl
 ])
 if test ! -f compiler/cmm/CmmLex.hs || test ! -f compiler/parser/Lexer.hs
 then
-    FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-lt],[2.0],
-      [AC_MSG_ERROR([Alex version 2.0 or later is required to compile GHC.])])[]dnl
+    FP_COMPARE_VERSIONS([$fptools_cv_alex_version],[-lt],[2.0.1],
+      [AC_MSG_ERROR([Alex version 2.0.1 or later is required to compile GHC.])])[]dnl
 fi
 AlexVersion=$fptools_cv_alex_version;
 AC_SUBST(AlexVersion)