restore building perl5**.dll and perl.exe on WinCE

restore building perl5**.dll and perl.exe on WinCE

extension building problems remain but the 2 above files will build be
built for WinCE with the following 3 commands, replace the folder name with
what you selected for $(MACHINE) in makefile.ce

nmake all
nmake -f makefile.ce wince-x86-hpc-wce300\perl517.dll
nmake -f makefile.ce wince-x86-hpc-wce300\perl.exe

makefile.ce:
- -debug:full and -pdb:none are obsolete compiler flags,
  and add -opt:ref:icf, to sync eVC makefile with modern VC's makefile
- create a shortcut for easily creating preprocessed (.i) files for
  debugging on the command line
- add new interp .c files that were added over the years
- the Dynaloader build process for Win32 was drastically changed in
  commit 281da5eaa8 , fix to reflect this, a "nmake all" on the Win32 build
  will create the correct dynaloader .c files for the ce makefile to use
  later
- nothing depended on .\xconfig.h in the ce makefile, so there was an error
  that it was missing, fix that
- rebase the CE perl5**.dll to same as on Win32 makefile, makes
  debugging/diassembly much easier when the dll is not relocated at runtime
- config.sh seems to be a win32 build file, while the script configpm
  wants a .sh file in \Cross, so change config.sh dependency to that

win32/Makefile:
- add a preprocess target to easily create .i files for debugging by hand

makedef.pl:
- read the comments in the script
- config.h is Win32 file, not a WinCE file, so use xconfig.h when
  under WinCE

lib/.gitignore
- Cross.pm is made during the build process, it shouldn't ever be commited

win32/.gitignore
- xconfig.h is made during the build process, it shouldn't ever be commited

win32/wince.c
- identifier isnan is defed to _isnan somewhere, this created an infinite
  loop when CE perl was run