Make sure that all globals are internal, except for "start" functions.

tests_lit/reader_tests/extern_globals.ll

 ; Test whether we don't mangle external, undefined, global names. This
 ; feature is needed for cross tests on global initializer relocations.
 ;
 ; Note: This code was generated by compiling subzero/crosstest/test_global.cpp
 
 ; We use lc2i (rather than p2i) because PNaCl bitcode files do not
 ; allow externally defined global variables. Hence, this test can only
 ; work if we read LLVM IR source, and convert to to ICE.
 
 ; REQUIRES: allow_llvm_ir_as_input
-; RUN: %lc2i -i %s --insts --args --allow-uninitialized-globals | FileCheck %s
 ; RUN: %lc2i -i %s --insts --args --allow-uninitialized-globals \
+; RUN:       -allow-externally-defined-symbols | FileCheck %s
+; RUN: %lc2i -i %s --insts --args --allow-uninitialized-globals \
+; RUN:       -allow-externally-defined-symbols \
 ; RUN:       -prefix Subzero_ | FileCheck --check-prefix=CROSS %s
 
 @ArrayInitPartial = internal global [40 x i8] c"<\00\00\00F\00\00\00P\00\00\00Z\00\00\00d\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 4
 
 ; CHECK: @ArrayInitPartial = internal global [40 x i8] c"<\00\00\00F\00\00\00P\00\00\00Z\00\00\00d\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 4
 ; CROSS: @Subzero_ArrayInitPartial = internal global [40 x i8] c"<\00\00\00F\00\00\00P\00\00\00Z\00\00\00d\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 4
 
 @ArrayInitFull = internal global [20 x i8] c"\0A\00\00\00\14\00\00\00\1E\00\00\00(\00\00\002\00\00\00", align 4
 
 ; CHECK: @ArrayInitFull = internal global [20 x i8] c"\0A\00\00\00\14\00\00\00\1E\00\00\00(\00\00\002\00\00\00", align 4
@@ skipping 236 matching lines @@
 define i32 @nacl_tp_tdb_offset(i32) {
 entry:
   ret i32 0
 }
 
 define i32 @nacl_tp_tls_offset(i32 %size) {
 entry:
   %result = sub i32 0, %size
   ret i32 %result
 }