Unbreak build on legacy Darwin

Perl#21023
Perl-Toolchain-Gang/ExtUtils-MakeMaker#444

Author: sevan

cpan/ExtUtils-MakeMaker/lib/ExtUtils/MM_Darwin.pm

@@ -46,29 +46,4 @@ sub init_dist {
     $self->SUPER::init_dist(@_);
 }
 
-=head3 cflags
-
-Over-ride Apple's automatic setting of -Werror
-
-=cut
-
-sub cflags {
-    my($self,$libperl)=@_;
-    return $self->{CFLAGS} if $self->{CFLAGS};
-    return '' unless $self->needs_linking();
-
-    my $base = $self->SUPER::cflags($libperl);
-
-    foreach (split /\n/, $base) {
-        /^(\S*)\s*=\s*(\S*)$/ and $self->{$1} = $2;
-    };
-    $self->{CCFLAGS} .= " -Wno-error=implicit-function-declaration";
-
-    return $self->{CFLAGS} = qq{
-CCFLAGS = $self->{CCFLAGS}
-OPTIMIZE = $self->{OPTIMIZE}
-PERLTYPE = $self->{PERLTYPE}
-};
-}
-
 1;

dist/ExtUtils-CBuilder/lib/ExtUtils/CBuilder/Platform/darwin.pm

@@ -20,9 +20,6 @@ sub compile {
   local $cf->{ccflags} = $cf->{ccflags};
   $cf->{ccflags} =~ s/-flat_namespace//;
 
-  # XCode 12 makes this fatal, breaking tons of XS modules
-  $cf->{ccflags} .= ($cf->{ccflags} ? ' ' : '').'-Wno-error=implicit-function-declaration';
-
   $self->SUPER::compile(@_);
 }