Const-correctness.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81249 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/Unix/Program.inc b/lib/System/Unix/Program.inc
index ce75710..f5290b4 100644
--- a/lib/System/Unix/Program.inc
+++ b/lib/System/Unix/Program.inc
@@ -38,7 +38,7 @@
 
 Program::~Program() {}
 
-unsigned Program::GetPid() {
+unsigned Program::GetPid() const {
   return reinterpret_cast<unsigned>(Data_);
 }