autoconf: 2.59 -> 2.61

[DJ Delorie]

In src/newlib/ all the configure files have been generated with autoconf 2.61 except
these three:

newlib/libm/machine/spu/configure:# Generated by GNU Autoconf 2.59 for newlib 1.15.0.
newlib/libc/sys/configure:# Generated by GNU Autoconf 2.59 for newlib 1.15.0.
newlib/libc/machine/configure:# Generated by GNU Autoconf 2.59 for newlib 1.15.0.

Can we convert those too?  Otherwise, you get the occasional error like this:

configure: loading cache .././config.cache
configure: error: `CXXFLAGS' has changed since the previous run:
configure:   former value:  -g -O2  -D_GNU_SOURCE
configure:   current value: -g -O2 -D_GNU_SOURCE
configure: error: changes in the environment can compromise the build

(note the change in whitespace - this is fixed in 2.61)

Also, in libgloss, they're all 2.59.  Can those be upgraded?