The newlib & libgloss dirs are already generated using autoconf-2.69.
To avoid merging new code and/or accidental regeneration using diff
versions, leverage config/override.m4 to pin to 2.69 exactly. This
matches what gcc/binutils/gdb are already doing.
The README file already says to use autoconf-2.69.
To accomplish this, it's just as simple as adding -I flags to the
top-level config/ dir when running aclocal. This is because the
override.m4 file overrides AC_INIT to first require the specific
autoconf version before calling the real AC_INIT.
The configure scripts were regenerated with 2.69 for the newlib-4.2.0
release in 484d2ebf8d825b28af47b8ee88cd845f1d2c7c6e, but the aclocal
files were not. Do that now to avoid confusion between the two as to
which version of autoconf was used.
