Fix the Linux build.

Change-Id: I2c06dbe89f8e079f690242cd97af6638087af593
Reviewed-on: https://swiftshader-review.googlesource.com/1394
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Common/Configurator.cpp b/src/Common/Configurator.cpp
index 94fbe68..2a8ad16 100644
--- a/src/Common/Configurator.cpp
+++ b/src/Common/Configurator.cpp
@@ -20,6 +20,10 @@
 #include <stdarg.h>
 #include <ctype.h>
 
+#if defined(__unix__)
+#include <unistd.h>
+#endif
+
 namespace sw
 {
 	Configurator::Configurator(string iniPath)