Fix --rakudo-home Configure.pl parameter

`Perl6::SysConfig` object construction was broken in so far as the
%rakudo-build-config hash was initialized externally after object
construction and thus wasn't available in the `BUILD()` method itself but
was used there. This is fixed by passing a pre-populated
%rakudo-build-config hash to the Perl6::SysConfig constructor.

src/Perl6/SysConfig.nqp

@@ -2,8 +2,16 @@ class Perl6::SysConfig is HLL::SysConfig {
     has %!rakudo-build-config;
     has $!rakudo-home;
 
-    method BUILD() {
-        %!rakudo-build-config := nqp::hash();
+    method new(%rakudo-build-config) {
+        my $obj := nqp::create(self);
+        $obj.BUILD(%rakudo-build-config);
+        $obj
+    }
+
+    method BUILD(%rakudo-build-config) {
+        self.build-hll-sysconfig();
+
+        %!rakudo-build-config := %rakudo-build-config;
 
         # Determine Rakudo home.
         my $execname := nqp::execname();

src/main.nqp

@@ -7,8 +7,9 @@ use Perl6::SysConfig;
 # Initialize Rakudo runtime support.
 nqp::p6init();
 
-nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new());
-hll-config(nqp::gethllsym('default', 'SysConfig').rakudo-build-config);
+my %rakudo-build-config := nqp::hash();
+hll-config(%rakudo-build-config);
+nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new(%rakudo-build-config));
 
 # Create and configure compiler object.
 my $comp := Perl6::Compiler.new();

src/rakudo-debug.nqp

@@ -454,8 +454,9 @@ sub MAIN(*@ARGS) {
     # Initialize dynops.
     nqp::p6init();
 
-    nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new());
-    hll-config(nqp::gethllsym('default', 'SysConfig').rakudo-build-config);
+    my %rakudo-build-config := nqp::hash();
+    hll-config(%rakudo-build-config);
+    nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new(%rakudo-build-config));
 
     # Create and configure compiler object.
     my $comp := Perl6::Debugger.new();

src/vm/js/load-compiler.nqp

@@ -3,8 +3,9 @@ use Perl6::Actions;
 use Perl6::Compiler;
 use Perl6::SysConfig;
 
-nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new());
-hll-config(nqp::gethllsym('default', 'SysConfig').rakudo-build-config);
+my %rakudo-build-config := nqp::hash();
+hll-config(%rakudo-build-config);
+nqp::bindhllsym('default', 'SysConfig', Perl6::SysConfig.new(%rakudo-build-config));
 
 # Create and configure compiler object.
 my $comp := Perl6::Compiler.new();