[Module::Build] ExtUtils::CBuilder: cygwin gcc in mingw mode misparses command line

[Yitzchak Scott-T. <sth...@ef...>]

Cygwin programs when run by non-cygwin programs do not interpret \" as
an escaped " except within "".  This results in errors like the
following when using cygwin gcc in "mingw" mode:

gcc -mno-cygwin -c -s -O2 -DWIN32 -DHAVE_DES_FCRYPT -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fno-strict-aliasing -DPERL_MSVCRT_READFIX -s -O2 -DXS_VERSION=\"0.01\" -DVERSION=\"0.01\" -I"..\..\..\lib\CORE" -I"C:\MinGW\include" -o "lib\Simple.o" "lib\Simple.c"
gcc: no input files
error building dll file from 'lib\Simple.c' at C:\cygwin\home\sthoenna\bleadperl\wp\lib/ExtUtils/CBuilder/Platform/Windows.pm line 143.

The first backslash in -DXS_VERSION=\"0.01\" is treated as a literal
backslash, and the " after it starts a quoted string, resulting in gcc
getting everything after -O2 as a single argument:

  -DXS_VERSION=\0.01" -DVERSION="0.01" -I......libCORE -IC:MinGWinclude -o libSimple.o libSimple.c

The following patch fixes this and in theory should not cause any
problems.

--- lib/ExtUtils/CBuilder/Platform/Windows.pm.orig	2005-10-04 04:32:20.000000000 -0700
+++ lib/ExtUtils/CBuilder/Platform/Windows.pm	2006-01-09 19:55:07.807132800 -0800
@@ -93,7 +93,7 @@
 sub arg_defines {
   my ($self, %args) = @_;
   s/"/\\"/g foreach values %args;
-  return map "-D$_=$args{$_}", keys %args;
+  return map qq{"-D$_=$args{$_}"}, keys %args;
 }
 
 sub compile {