Remove Boost from distribution and fix some more things for Windows compilation

xs/src/libslic3r/Config.cpp

@@ -1,7 +1,7 @@
 #include "Config.hpp"
 #include <stdlib.h>  // for setenv()
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(setenv) && defined(_putenv_s)
 #define setenv(k, v, o) _putenv_s(k, v)
 #endif
 
@@ -104,6 +104,7 @@ ConfigBase::get_abs_value(const t_config_option_key &opt_key, double ratio_over)
 void
 ConfigBase::setenv_()
 {
+#ifdef setenv
     t_config_option_keys opt_keys = this->keys();
     for (t_config_option_keys::const_iterator it = opt_keys.begin(); it != opt_keys.end(); ++it) {
         // prepend the SLIC3R_ prefix
@@ -118,6 +119,7 @@ ConfigBase::setenv_()
         
         setenv(envname.c_str(), this->serialize(*it).c_str(), 1);
     }
+#endif
 }
 
 #ifdef SLIC3RXS