Build failure on macOS 10.15

[Bo Lindbergh]

./configure now says this:
> checking if /Library/Developer/CommandLineTools/usr/bin/ld supports -Wl,-z,relro... no
> checking if /Library/Developer/CommandLineTools/usr/bin/ld supports -Wl,-z,now... no

... and everything builds.  Looks good.

I think the description is a bit off, though: the "-Wl,-z,relro" option
is passed to the C compiler, not to the linker.


/Bo Lindbergh