src: define getpid() based on OS

94b9948 added unistd.h to src/env.cc in order to use getpid(). However, this doesn't exist on Windows. This commit conditionally defines getpid() based on the OS. Fixes: #4145 PR-URL: #4146 Reviewed-By: Brian White <[email protected]>

Author: cjihrig

src/env.cc

@@ -1,6 +1,13 @@
 #include"env.h"
 #include"env-inl.h"
 #include"v8.h"
+
+#if defined(_MSC_VER)
+#definegetpid GetCurrentProcessId
+#else
+#include<unistd.h>
+#endif
+
 #include<stdio.h>
 
 namespacenode{