putenv: port better to native Windows * lib/putenv.c [(_WIN32 || __WIN32__) && ! __CYGWIN__]: Define WIN32_LEAN_AND_MEAN and include <windows.h>. (_unsetenv): Use _putenv if available. (putenv): Temporarily set NAME=' ' rather than NAME='x' as that's a bit less likely to cause damage. (putenv) [(_WIN32 || __WIN32__) && ! __CYGWIN__]: Fix the wrong value with SetEnvironmentVariable. (putenv) [!HAVE__PUTENV]: Simplify and match the HAVE__PUTENV code better.

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testdir*