func_emit_cwrapperexe_src() errors with mingw32ce

[Vincent Torri]

Hey,

Natively, the Windows CE OS has no concept of environment variable. Hence, 
when mingw32ce is used, func_emit_cwrapperexe_src() fails because of 
missing getenv() and putenv() (or setenv() also, of course). I don't know 
what to do here (removing or not thee calls, as I don't know why they are 
used.

There are also 2 other functions that are missing with that compiler:

 * getcwd()

  it's possible to get the path where the current process is launched. 
Again, i don't know if it's simpler to remove that call or if one should 
provide a way to have the path where the process is launched.

 * _spawnv()

  i don't know any simple way to fake that function. Maybe one should add 
another test in the 'host' case for that specific compiler which wo do 
nothing (in that case, one can remove the #ifndef in the case the host is 
mingw*)

Vincent Torri