Avoid shell quoting issues in build system

Double quotes may have different meaning on different systems. Avoid that trap
by running the perl binary directly instead of through some shell.

Should fix GH #1728

Build.pm

@@ -3,10 +3,10 @@ use LibraryMake;
 
 class Build {
     method build($dir) {
-        shell('perl -e "use v5.18;"')
+        run('perl', '-e', 'use v5.18;')
             or die "\nPerl 5 version requirement not met\n";
 
-        shell('perl -MFilter::Simple -e ""')
+        run('perl', '-MFilter::Simple', '-e', '')
             or die "\nPlease install the Filter::Simple Perl 5 module!\n";
 
         my %vars = get-vars($dir);

configure.pl6

@@ -8,10 +8,10 @@ sub MAIN(:$test, :$install is copy) {
 }
 
 sub configure() {
-    shell('perl -e "use v5.18;"')
+    run('perl', '-e', 'use v5.18;')
         or die "\nPerl 5 version requirement not met\n";
 
-    shell('perl -MFilter::Simple -e ""')
+    run('perl', '-MFilter::Simple', '-e', '')
         or die "\nPlease install the Filter::Simple Perl 5 module!\n";
 
     my %vars;