[llvm-objcopy] Append '\n' to warning messages

[MaskRay]

Summary

Currently the warning message of llvm-strip %t.o %t.o does not include
the trailing newline. Fix this by appending a '\n'.

This is the only warning llvm-objcopy and llvm-strip can issue.

[jhenderson]

LGTM! Thanks!

llvm/trunk/test/tools/llvm-objcopy/ELF/same-file-strip.test

 ## Test llvm-strip using the same input file more than once.
 ## When using stdin ('-') more than once llvm-strip should give an error
 ## while a file more than once should be simply a warning.
 
 # RUN: yaml2obj %s -o %t
 
 # RUN: not llvm-strip - - < %t 2>&1 | FileCheck -check-prefix=ERR %s
 # RUN: not llvm-strip - %t - < %t 2>&1 | FileCheck -check-prefix=ERR %s
 
 # ERR: error: cannot specify '-' as an input file more than once
 
-# RUN: llvm-strip %t %t 2>&1 | FileCheck -check-prefix=WARN %s -DFILE=%t
-# RUN: llvm-strip %t %t %t 2>&1 | FileCheck -check-prefix=WARN %s -DFILE=%t
+# RUN: cp %t %t2
+# RUN: llvm-strip %t %t %t %t2 %t2 2>&1 | FileCheck -check-prefix=WARN %s -DFILE=%t -DFILE2=%t2
 
-# WARN: warning: '[[FILE]]' was already specified
+# WARN:      warning: '[[FILE]]' was already specified
+# WARN-NEXT: warning: '[[FILE2]]' was already specified
 
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_REL
   Machine: EM_X86_64
 Sections:
   - Name:  .alloc
     Type:  SHT_PROGBITS
     Flags: [ SHF_ALLOC ]

llvm/trunk/tools/llvm-objcopy/llvm-objcopy.cpp

LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, Error E) {
   logAllUnhandledErrors(std::move(E), OS);
   OS.flush();
   WithColor::error(errs(), ToolName) << "'" << File << "': " << Buf;
   exit(1);
 }
 
 ErrorSuccess reportWarning(Error E) {
   assert(E);
-  WithColor::warning(errs(), ToolName) << toString(std::move(E));
+  WithColor::warning(errs(), ToolName) << toString(std::move(E)) << '\n';
   return Error::success();
 }
 
 } // end namespace objcopy
 } // end namespace llvm
 
 using namespace llvm;
 using namespace llvm::object;