Most implicit function declarations left come from the included libiberty.
Add it to eautoreconf to regenerate its tests.
https://bugs.gentoo.org/898594

--- a/configure.ac
+++ b/configure.ac
@@ -874,7 +874,7 @@
 test $OPT_DISABLE_PACKIHX = 0 && AC_CONFIG_SUBDIRS(support/packihx)
 test $OPT_DISABLE_UCSIM   = 0 && AC_CONFIG_SUBDIRS(sim/ucsim)
 test $OPT_DISABLE_SDCDB   = 0 && AC_CONFIG_SUBDIRS(debugger/mcs51)
-test $OPT_DISABLE_SDBINUTILS = 0 && AC_CONFIG_SUBDIRS(support/sdbinutils)
+test $OPT_DISABLE_SDBINUTILS = 0 && AC_CONFIG_SUBDIRS(support/sdbinutils support/sdbinutils/libiberty)
 AC_CONFIG_FILES([doc/Makefile])
 
 ####test $OPT_DISABLE_AVR = 0 && AC_CONFIG_FILES([src/avr/Makefile])