agrep: Disable implicit function declaration errors

This is not ideal but fixing the code properly requires extensive work
and the developer has been unresponsive to a pull request with an
initial partial set of fixes.

See: https://trac.macports.org/ticket/68759

sysutils/agrep/Portfile

@@ -23,6 +23,11 @@ checksums           rmd160  818f69f751943ddd8d6b2410b95bac1667985d0a \
 
 extract.suffix      .tar.Z
 
+# https://github.com/Wikinaut/agrep/issues/20
+supported_archs     i386 ppc ppc64 x86_64
+configure.cflags-append \
+                    -Wno-error=implicit-function-declaration
+
 patchfiles          return_types.patch warnings.patch
 
 use_configure       no