* configure: added case for Cygwin to translate shared module

* configure: added case for Cygwin to translate shared module
extensions from .so to .dll. Almost the same as for OS2.

* htdocs/manual/cywin.html: added related changes to the configure
and build process for shared module DLLs.

* src/Configure: cleaned up Cygwin case for OS specific variable
declaration. Removed no longer need $DLL_IMPORT_DEF and
$DLL_IMPORT_LIB variables.

* src/Makefile.tmpl: removed no longer needed $DLL_IMPORT_LIB
variable.

* src/main/http_main.c: added dllexport declaration for int REALMAIN
for SHARED_CORE support.

* src/modules/standard/Makefile.Cygwin: added this new file to
reflect the extra rules needed to link the shared module DLLs. Very
similar to src/modules/standard/Makefile.OS2.

* src/os/cygwin/os.h: added explicit dllimport and dllexport
declarations for API_VAR_EXPORT and API_EXPORT(type).

PR:
Obtained from:
Submitted by:	Stipe Tolj <tolj@wapme-systems.de>
Reviewed by:

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@91166 13f79535-47bb-0310-9956-ffa450edef68