LLVM: Add ELF Note section to NaCl object files identifying them as such to gold

test/MC/X86/elf-note-nacl.ll

+; RUN: llc -filetype=obj -mtriple i686-none-nacl %s -o - \
+; RUN:   | llvm-objdump -triple i686 -s - | FileCheck --check-prefix=I386 %s
+
+; RUN: llc -filetype=obj -mtriple x86_64-none-nacl %s -o - \
+; RUN:   | llvm-objdump -triple x86_64 -s - | FileCheck --check-prefix=X8664 %s
+
+; Tests that NaCl object files contain an ELF note section that identifies them
+; to the binutils gold linker
+
+define void @main() {
+  ret void
+}
+
+; There appears to be no way for llvm-objdump to show flags for sections, or
+; to dump groups like readelf.
+; I386: .group
+; I386: .note.NaCl.ABI.x86-32
+; The contents of the words in the note section should be:
+;   sizeof "NaCl"
+;   sizeof "x86-32"
+;   1 (NT_VERSION)
+;   "NaCl" with nul termination and padding to align 4
+;   "x86-32" with nul termination and padding to align 4
+; I386-NEXT: 0000 05000000 07000000 01000000 4e61436c
+; I386-NEXT: 0010 00000000 7838362d 33320000
+
+; X8664: .group
+; X8664: .note.NaCl.ABI.x86-64
+; The contents of the words in the note section should be:
+;   sizeof "NaCl"
+;   sizeof "x86-64"
+;   1 (NT_VERSION)
+;   "NaCl" with nul termination and padding to align 4
+;   q"x86-64" with nul termination and padding to align 4
+; X8664-NEXT: 0000 05000000 07000000 01000000 4e61436c
+; X8664-NEXT: 0010 00000000 7838362d 36340000