Find Perl embedding options at configure time

This removes the dependency on command interpolation in makefiles, hopefully
unbreaking nmake, and is in any event a neccessary step towards supporting
compilation on non-default Perls.

Configure.pl

@@ -21,6 +21,8 @@ =head1 SYNOPSIS
 
 use Getopt::Long qw(:config auto_help);
 
+use ExtUtils::Embed;
+
 our ( $opt_parrot_config, $opt_gen_parrot);
 GetOptions( 'parrot-config=s', 'gen-parrot' );
 
@@ -51,6 +53,10 @@ =head1 SYNOPSIS
         ."Please give me the path to it with the --parrot-config=... option.";
 }
 
+$config{p5_ldopts} = ldopts(1);
+$config{p5_ccopts} = ccopts(1);
+$config{p5_perl} = $^X;
+
 #  Create the Makefile using the information we just got
 create_makefile('Makefile' => %config);
 create_makefile('src/pmc/Makefile' => %config);
@@ -79,7 +85,8 @@ sub create_makefile {
     my $maketext = slurp( "build/$name.in" );
 
     $config{'win32_libparrot_copy'} = $^O eq 'MSWin32' ? 'copy $(PARROT_BIN_DIR)\libparrot.dll .' : '';
-    $maketext =~ s/@(\w+)@/$config{$1}/g;
+    $maketext =~ s{#IF\((\w+)\):(.*\n)}{$config{osname} eq $1 ? $2 : ""}eg;
+    $maketext =~ s/@(\w+)@/exists $config{$1} ? $config{$1} : die("No such config var $1")/eg;
     if ($^O eq 'MSWin32') {
         $maketext =~ s{/}{\\}g;
         $maketext =~ s{\\\*}{\\\\*}g;

build/Makefile.in

@@ -20,7 +20,7 @@ PMC_DIR       = src/pmc
 
 ## Setup some commands
 MAKE          = @make_c@
-PERL          = @perl@
+PERL          = @p5_perl@
 CAT           = @cat@
 CHMOD         = @chmod@
 CP            = @cp@

build/src/pmc/Makefile.in

@@ -10,15 +10,12 @@ STAGING_DIR   = ../../dynext
 #INSTALL_DIR   = $(LIB_DIR)/languages/blizkost/dynext
 INSTALL_DIR   = $(LIB_DIR)/dynext
 
-EMBLFLAGS := $(shell perl -MExtUtils::Embed -e ldopts)
-EMBCFLAGS := $(shell perl -MExtUtils::Embed -e ccopts)
-
 # Set up extensions
 LOAD_EXT      = @load_ext@
 O             = @o@
 
 # Setup some commands
-PERL          = @perl@
+PERL          = @p5_perl@
 RM_F          = @rm_f@
 MKPATH        = @mkpath@
 CHMOD         = @chmod@
@@ -27,7 +24,7 @@ CC            = @cc@ -c
 LD            = @ld@
 LDFLAGS       = @ldflags@ @ld_debug@ @libs@
 LD_LOAD_FLAGS = @ld_load_flags@
-CFLAGS        = @ccflags@ @cc_shared@ @cc_debug@ @ccwarn@ @cc_hasjit@ @cg_flag@ @gc_flag@ $(EMBCFLAGS)
+CFLAGS        = @ccflags@ @cc_shared@ @cc_debug@ @ccwarn@ @cc_hasjit@ @cg_flag@ @gc_flag@ @p5_ccopts@
 CC_OUT        = @cc_o_out@
 LD_OUT        = @ld_out@
 LIBPARROT     = @inst_libparrot_ldflags@
@@ -38,7 +35,7 @@ PMC2CD          = $(PMC2C) --dump $(PMC2C_INCLUDES)
 PMC2CC          = $(PMC2C) -c $(PMC2C_INCLUDES)
 
 INCLUDES        = -I$(INCLUDE_DIR) -I$(INCLUDE_DIR)/pmc
-LINKARGS        = $(LDFLAGS) $(LD_LOAD_FLAGS) $(LIBPARROT) $(EMBLFLAGS)
+LINKARGS        = $(LDFLAGS) $(LD_LOAD_FLAGS) $(LIBPARROT) @p5_ldopts@
 
 BLIZKOST_GROUP = blizkost_group