Ticket #1905: fix of version calculation.

configure: line 2188: 0: command not found

This error occurs due to incorrect processing of grep command output.
This commit fixed that issue.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

m4.include/mc-version.m4

@@ -22,7 +22,7 @@ AC_DEFUN([MC_VERSION],[
     DISTR_VERSION=`echo $VERSION | sed 's/^\([[^\-]]*\).*/\1/'`
     DISTR_RELEASE=`echo $VERSION | sed 's/^[[^\-]]*\-\(.*\)/\1/' | sed 's/-/./g'`
 
-    if `echo $VERSION | grep -c '\-pre'`; then
+    if test `echo $VERSION | grep -c '\-pre'` -ne 0; then
         DISTR_RELEASE="0.$DISTR_RELEASE"
     else
         if test `echo $VERSION | grep -c '\-'` -eq 0; then