configure: Pass LDFLAGS to link tests

[kraj]

LDFLAGS can contain critical flags without which linking wont succeed therefore ensure that all configure tests involving link time checks are using LDFLAGS on compiler commandline along with CFLAGS to ensure the tests perform correctly. Without this some tests may fail resulting in wrong confgure result, ending in miscompiling the package

Upstream-Status: Pending

Signed-off-by: Khem Raj [email protected]

[kraj]

@madler I have rebased this patch. adding LDFLAGS improves the situation especially for cross-compiling environments like Yocto.