portability: define uid_t and gid_t

Summary:
The getuid and getgid are defined as returning uid_t and gid_t. Defining these
types here will prevent downstream consumer from having to redefine these
types for Windows.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum, Orvid

Differential Revision: D23693492

fbshipit-source-id: 1ec9221509bffdd5f6d241c4bc08d7809cdb6162

folly/portability/SysTypes.h

@@ -25,6 +25,10 @@
 // we support, but it's far more compatible with the rest of the windows world
 // as an `int` than it would be as a `void*`
 using pid_t = int;
+
+using uid_t = int;
+using gid_t = int;
+
 // This isn't actually supposed to be defined here, but it's the most
 // appropriate place without defining a portability header for stdint.h
 // with just this single typedef.

folly/portability/Unistd.cpp

@@ -115,7 +115,7 @@ int getdtablesize() {
   return _getmaxstdio();
 }
 
-int getgid() {
+gid_t getgid() {
   return 1;
 }
 
@@ -125,7 +125,7 @@ pid_t getppid() {
   return (pid_t)1;
 }
 
-int getuid() {
+uid_t getuid() {
   return 1;
 }