The compiler flag tests for -gz=zlib and -gz=zlib-gnu currently use AC_COMPILE_IFELSE, but as these are basically linker flags it appears this is just checking that the frontend supports them.

For example if binutils is configured so that gold is the default linker the tests pass:

checking if gcc accepts -g -gz=zlib... yes
checking if gcc accepts -g -gz=zlib-gnu... yes

but the actual use of them fails:

| x86_64-poky-linux-gcc: error: -gz=zlib is not supported in this configuration

Changing AC_COMPILE_IFELSE to AC_LINK_IFELSE means that configure detects that -gz=zlib doesn't work but zlib-gnu does, and the build works.