configure warnings with -mno-cygwin option

[g.paulissen]

When I run

Platform: cygwin

$ configure CFLAGS="-mno-cygwin"

I get the following warnings

configure: WARNING: dlfcn.h: present but cannot be compiled
configure: WARNING: dlfcn.h: check for missing prerequisite headers?
configure: WARNING: dlfcn.h: proceeding with the preprocessor's result
configure: WARNING:     ## ------------------------------------ ##
configure: WARNING:     ## Report this to address@hidden ##
configure: WARNING:     ## ------------------------------------ ##

configure: WARNING: dlfcn.h: present but cannot be compiled
configure: WARNING: dlfcn.h: check for missing prerequisite headers?
configure: WARNING: dlfcn.h: proceeding with the preprocessor's result
configure: WARNING:     ## ------------------------------------ ##
configure: WARNING:     ## Report this to address@hidden ##
configure: WARNING:     ## ------------------------------------ ##

configure: WARNING: sys/resource.h: present but cannot be compiled
configure: WARNING: sys/resource.h: check for missing prerequisite headers?
configure: WARNING: sys/resource.h: proceeding with the preprocessor's result
configure: WARNING:     ## ------------------------------------ ##
configure: WARNING:     ## Report this to address@hidden ##
configure: WARNING:     ## ------------------------------------ ##

Regards,

Gert-Jan Paulissen