Fix cross-compilation

Fix cross-compilation

Using AC_RUN_IFELSE() in configure.ac breaks cross-compilation:

    configure: error: cannot run test program while cross compiling

Commit 978c7b2e89aa37a7ddfe2f6b6ba12ce73dd04528 caused AC_RUN_IFELSE()
to be used instead of AC_LINK_IFELSE() because the latter had seemingly
been causing the check for --wrap support in the linker to not work as
expected.  However, it later turned out that the problem lied elsewhere:
a minus sign ('-') was missing from the LDFLAGS variable used in the
relevant check [1].

Revert to using AC_LINK_IFELSE() for checking whether the linker
supports the --wrap option in order to make cross-compilation possible
again.

[1] see commit cfa4ea64bc06685f210a4187dcc05cc0aac84851