[...]'sed-4.0.7' builds out of the box in MSYS, but 'sed-4.1.4' seems
to need a few manual changes:
Apparently 'sed-4.1.5' would need some manual change of its own.
Copying an "alloca.h" from somewhere would be treating the
symptom rather than the cause; it would be better to look for a
checking for working alloca.h...
in the output of 'configure' and try to figure out why it wants
to use that header when the compiler doesn't provide it.
However, that whole approach will only produce a native binary
that's not MSYS aware--it'll have problems like this:
so you'll want to build 'sed' as an MSYS application:
if your goal is to use a recent version of 'sed' with MSYS.