Bug #51414: Arguments with embedded spaces are not correctly handled by configure wrapper.

The bug was that ./configure was  passing paramers to subscripts as $@, and to handle embedded spaces it needs
to be quoted as "$@".
This resulting into a bug when ./configure was called e.g with CFLAGS='-m64 -Xstrconst'..

Additionally, fixed cmake/configure.pl did not handle environment variables passed on the command line.
this is fixed in this push

BUILD/choose_configure.sh

@@ -7,8 +7,8 @@ cmake -P cmake/check_minimal_version.cmake >/dev/null 2>&1 || HAVE_CMAKE=no
 perl --version >/dev/null 2>&1 || HAVE_CMAKE=no
 if test "$HAVE_CMAKE" = "no"
 then
-  sh ./configure.am $@
+  sh ./configure.am "$@"
 else
-  perl ./cmake/configure.pl $@
+  perl ./cmake/configure.pl "$@"
 fi
 

cmake/configure.pl

@@ -72,10 +72,21 @@ check_compiler("CXX", "CXXFLAGS");
 
 foreach my $option (@ARGV)
 {
-  if (substr ($option, 0, 2) == "--")
+  if (substr ($option, 0, 2) eq "--")
   {
     $option = substr($option, 2);
   }
+  else
+  {
+    # This must be environment variable
+    my @v  = split('=', $option);
+    my $name = shift(@v);
+    if(@v)
+    {
+      $ENV{$name} = join('=', @v);  
+    }	
+    next;
+  }
   if($option =~ /srcdir/)
   {
     $srcdir = substr($option,7);