[llvm-pdbdump] Add support for dumping global variables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230744 91177308-0d34-0410-b5e6-96231b3b80d8

test/DebugInfo/PDB/Inputs/symbolformat.cpp

@@ -55,6 +55,9 @@ struct MemberTest {
 typedef int IntType;
 typedef A ClassAType;
 
+int g_global_int;
+void *g_global_pointer = nullptr;
+
 int main(int argc, char **argv) {
   // Force symbol references so the linker generates debug info
   B b;