Move construction of VERSION file to end of the build

re: #2521

Charlie Zender has discovered that the netcdf created file VERSION
conflicts with the C++ version file on OSX case-insensitive file systems,
and maybe other case-insensitvie file systems.

Note:
1. Cmake does not create the VERSION file
2. The VERSION file is not installed
3. It turns out that the VERSION file is not required by the autoconf build.

It is possible that clients or package build system (e.g apt or brew)
might use the VERSION file, so we cannot delete it altogether.

So as a fix, we move the creation of the VERSION file to after the
build is complete by inserting a all-local hook into netcdf-c/Makefile.am.

# Misc. other changes
1. Suppressed warning by making use of the systeminfo command contingent on the platform being Windows.

Makefile.am

@@ -217,3 +217,11 @@ install-data-hook:
 	@echo '| https://www.unidata.ucar.edu                                 |'
 	@echo '+-------------------------------------------------------------+'
 	@echo ''
+
+
+# Create the VERSION file after the build
+# in case it is being used by packagers
+all-local: liblib/libnetcdf.la
+	echo ${PACKAGE_VERSION} > VERSION
+# Remove the VERSION file
+CLEANFILES = VERSION

configure.ac

@@ -36,9 +36,10 @@ AC_SUBST([netCDF_SO_VERSION]) netCDF_SO_VERSION=20:0:1
 # pattered after the files generated by libhdf4, libhdf5.
 #####
 
-# Create the VERSION file, which contains the package version from
-# AC_INIT.
-echo AC_PACKAGE_VERSION>VERSION
+# Create the VERSION file, which contains the package version from AC_INIT.
+# This file is apparently unused. But see the bottom of Makefile.am
+# echo AC_PACKAGE_VERSION>VERSION
+
 AC_SUBST(PACKAGE_VERSION)
 
 AC_MSG_NOTICE([netCDF AC_PACKAGE_VERSION])
@@ -115,7 +116,11 @@ ISMSYS=yes
 fi
 
 # Get windows version info
+if text "x$ISMSVC" = xyes ; then
 WINVER=`systeminfo | sed -e '/^OS Version:/p' -ed | sed -e 's|[^0-9]*\([0-9.]*\).*|\1|'`
+else
+WINVER="0.0.0"
+fi
 WINVERMAJOR=`echo $WVER | sed -e 's|\([^.]*\)[.]\([^.]*\)[.]\(.*\)|\1|'`
 WINVERBUILD=`echo $WVER | sed -e 's|\([^.]*\)[.]\([^.]*\)[.]\(.*\)|\3|'`
 if test "x$WINVERMAJOR" = x ; then WINVERMAJOR=0; fi