ioutil: drop the code, deprecated in v0.10.0

The code for ioutil has been marked as deprecated in release
v0.10.0, 4 years ago.

Time to drop it!

Change-Id: I36dce1669ebe9acada5f9e752835c53e5214e3be
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6089
Tested-by: jenkins

src/helper/Makefile.am

@@ -18,7 +18,6 @@ noinst_LTLIBRARIES += %D%/libhelper.la
 	%D%/binarybuffer.h \
 	%D%/bits.h \
 	%D%/configuration.h \
-	%D%/ioutil.h \
 	%D%/list.h \
 	%D%/util.h \
 	%D%/types.h \
@@ -32,12 +31,6 @@ noinst_LTLIBRARIES += %D%/libhelper.la
 	%D%/jep106.inc \
 	%D%/jim-nvp.h
 
-if IOUTIL
-%C%_libhelper_la_SOURCES += %D%/ioutil.c
-else
-%C%_libhelper_la_SOURCES += %D%/ioutil_stubs.c
-endif
-
 %C%_libhelper_la_CFLAGS = $(AM_CFLAGS)
 if IS_MINGW
 # FD_* macros are sloppy with their signs on MinGW32 platform