tools: teach objdump about FILE aux records

Add support for file auxiliary symbol entries in COFF symbol tables.  A COFF
symbol table with a FILE entry is followed by sizeof(__FILE__) / 18 auxiliary
symbol records which contain the filename.  Read them and form the original
filename that the record contains.  Then display the name in the output.

llvm-svn: 206126
diff --git a/llvm/test/tools/llvm-objdump/Inputs/file.obj.coff-arm b/llvm/test/tools/llvm-objdump/Inputs/file.obj.coff-arm
new file mode 100755
index 0000000..a333a87
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/Inputs/file.obj.coff-arm
Binary files differ
diff --git a/llvm/test/tools/llvm-objdump/coff-file.test b/llvm/test/tools/llvm-objdump/coff-file.test
new file mode 100644
index 0000000..ba345b4
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/coff-file.test
@@ -0,0 +1,5 @@
+RUN: llvm-objdump -t %p/Inputs/file.obj.coff-arm | FileCheck %s
+
+CHECK: .file
+CHECK-NEXT: AUX /Users/compnerd/work/llvm/test/tools/llvm-readobj/Inputs/file.asm
+