Tools like this should be configurable in a cross or native file. In
particular, if we are cross-compiling (with an executable wrapper like
qemu-arm), the build system ld is not necessarily able to manipulate
host system objects.
Signed-off-by: Simon McVittie <smcv@collabora.com>
The goal of this commit is to reduce differences between the autotools and meson build.
With autotools AC_FUNC_ALLOCA was used which defines HAVE_ALLOCA_H, HAVE_ALLOCA,
C_ALLOCA. meson tried to replicate that with has_function() but alloca can be a macro
and and is named _alloca under Windows. Since we require a working alloca anyway
and only need to know if the header exists replace AC_FUNC_ALLOCA with a simple
AC_CHECK_HEADERS.
There is still one user of HAVE_ALLOCA in the embedded gnulib, but since alloca is
always provided through galloca.h just force define HAVE_ALLOCA there and add a comment.
The docs were mentioning alloca as an example for cross compiling. Since that variable no
longer exists now replace it with another one.
