Configure: Allow 'DEFINE[]=def'

DEFINE[] definitions end up pushed in @{$config{defines}} instead of
being added to the output file list of defines.  This allows for the
unusual case where we need something to be defined globally, so it
gets picked up by anything using $(CPPFLAGS).

Reviewed-by: Bernd Edlinger <[email protected]>
(Merged from openssl#9679)

Configure

@@ -1908,7 +1908,7 @@ if ($builder eq "unified") {
             qr/^\s*INCLUDE\[((?:\\.|[^\\\]])+)\]\s*=\s*(.*)\s*$/
             => sub { push @{$includes{$1}}, tokenize($expand_variables->($2))
                          if !@skip || $skip[$#skip] > 0 },
-            qr/^\s*DEFINE\[((?:\\.|[^\\\]])+)\]\s*=\s*(.*)\s*$/
+            qr/^\s*DEFINE\[((?:\\.|[^\\\]])*)\]\s*=\s*(.*)\s*$/
             => sub { push @{$defines{$1}}, tokenize($expand_variables->($2))
                          if !@skip || $skip[$#skip] > 0 },
             qr/^\s*DEPEND\[((?:\\.|[^\\\]])*)\]\s*=\s*(.*)\s*$/
@@ -2109,24 +2109,33 @@ EOF
             }
         }
 
-        foreach (keys %defines) {
-            my $dest = $_;
-            my $ddest = cleanfile($sourced, $_, $blddir);
+        foreach my $dest (keys %defines) {
+            my $ddest;
 
-            # If the destination doesn't exist in source, it can only be
-            # a generated file in the build tree.
-            if (! -f $ddest) {
-                $ddest = cleanfile($buildd, $_, $blddir);
-                if ($unified_info{rename}->{$ddest}) {
-                    $ddest = $unified_info{rename}->{$ddest};
+            if ($dest ne "") {
+                $ddest = cleanfile($sourced, $dest, $blddir);
+
+                # If the destination doesn't exist in source, it can only
+                # be a generated file in the build tree.
+                if (! -f $ddest) {
+                    $ddest = cleanfile($buildd, $dest, $blddir);
+                    if ($unified_info{rename}->{$ddest}) {
+                        $ddest = $unified_info{rename}->{$ddest};
+                    }
                 }
             }
-            foreach (@{$defines{$dest}}) {
-                m|^([^=]*)(=.*)?$|;
+            foreach my $v (@{$defines{$dest}}) {
+                $v =~ m|^([^=]*)(=.*)?$|;
                 die "0 length macro name not permitted\n" if $1 eq "";
-                die "$1 defined more than once\n"
-                    if defined $unified_info{defines}->{$ddest}->{$1};
-                $unified_info{defines}->{$ddest}->{$1} = $2;
+                if ($dest ne "") {
+                    die "$1 defined more than once\n"
+                        if defined $unified_info{defines}->{$ddest}->{$1};
+                    $unified_info{defines}->{$ddest}->{$1} = $2;
+                } else {
+                    die "$1 defined more than once\n"
+                        if grep { $v eq $_ } @{$config{defines}};
+                    push @{$config{defines}}, $v;
+                }
             }
         }
     }