Rename _doprnt -> _bfd_doprnt to fix DJGPP bfd build (and likely others)

Building bfd/ for DJGPP, I see:

 ../../src/bfd/bfd.c:642:1: error: conflicting types for '_doprnt'
  _doprnt (FILE *stream, const char *format, va_list ap)
  ^~~~~~~
 In file included from ../../src/bfd/sysdep.h:37:0,
		  from ../../src/bfd/bfd.c:367:
 /usr/lib64/gcc/i586-pc-msdosdjgpp/6.1.0/include-fixed/stdio.h:171:5: note: previous declaration of '_doprnt' was here
  int _doprnt(const char *_fmt, va_list _args, FILE *_f);
      ^~~~~~~

Possible fixes the build on other systems too -- _doprnt was/is an
exported symbol on old Unix/BSD systems too.

bfd/ChangeLog:
2017-10-11  Pedro Alves  <palves@redhat.com>

	* bfd.c (_doprnt): Rename to ...
	(_bfd_doprnt): ... this.
	(error_handler_internal): Adjust.

1 files changed, 7 insertions, 6 deletions

diff --git a/bfd/bfd.c b/bfd/bfd.c
index f21c97a..7d6185f 100644
--- a/bfd/bfd.c
+++ b/bfd/bfd.c
@@ -626,10 +626,11 @@ CODE_FRAGMENT
 
 static const char *_bfd_error_program_name;
 
-/* This macro and _doprnt taken from libiberty _doprnt.c, tidied a
-   little and extended to handle '%A' and '%B'.  'L' as a modifer for
-   integer formats is used for bfd_vma and bfd_size_type args, which
-   vary in size depending on BFD configuration.  */
+/* This macro and _bfd_doprnt (originally _doprint) taken from
+   libiberty _doprnt.c, tidied a little and extended to handle '%A'
+   and '%B'.  'L' as a modifer for integer formats is used for bfd_vma
+   and bfd_size_type args, which vary in size depending on BFD
+   configuration.  */
 
 #define PRINT_TYPE(TYPE) \
   do								\
@@ -639,7 +640,7 @@ static const char *_bfd_error_program_name;
     } while (0)
 
 static int
-_doprnt (FILE *stream, const char *format, va_list ap)
+_bfd_doprnt (FILE *stream, const char *format, va_list ap)
 {
   const char *ptr = format;
   char specifier[128];
@@ -883,7 +884,7 @@ error_handler_internal (const char *fmt, va_list ap)
   else
     fprintf (stderr, "BFD: ");
 
-  _doprnt (stderr, fmt, ap);
+  _bfd_doprnt (stderr, fmt, ap);
 
   /* On AIX, putc is implemented as a macro that triggers a -Wunused-value
      warning, so use the fputc function to avoid it.  */