ruby31: Remove inappropriate -std=c99.

The Portfile has been carrying the -std=c99 setting (for OS <10.7)
forward through many versions, but that has been inappropriate since
ruby30, when the compiler selection was switched by the thread-local
storage requirement.  Since the compiler now defaults to C11,
specifying C99 is a step backward.  This removes that inappropriate
setting.

Since this is not known not to impact the installed content, it
includes a revbump.

Also, since the latest legacy-support includes fgetattrlist(), builds
for <10.6 no longer include the private fallback, making the installed
content different on those platforms.  The revbump covers that as
well.

Also removes unnecessary "platforms darwin", making lint happy.

TESTED:
Minimally tested on unaffected 10.7+.
Built with all variants except jemalloc on 10.5 ppc, and all variants
on 10.6 i386 and 10.6 x86_64.
Builds on other affected platforms known to be broken (as before).
Tests not run due to test framework issues.

lang/ruby31/Portfile

@@ -14,11 +14,10 @@ set ruby_patch      4
 set ruby_ver_nodot  [string map {. {}} ${ruby_ver}]
 name                ruby${ruby_ver_nodot}
 version             ${ruby_ver}.${ruby_patch}
-revision            0
+revision            1
 
 categories          lang ruby
 maintainers         {kimuraw @kimuraw} openmaintainer
-platforms           darwin
 
 description         Powerful and clean object-oriented scripting language
 long_description    Ruby is the interpreted scripting language for quick \
@@ -166,7 +165,6 @@ platform darwin {
         depends_build-append    port:gmake
         build.cmd               ${prefix}/bin/gmake
         configure.args-append   --disable-dtrace
-        configure.cflags-append -std=c99
     }
 
     if {${os.major} == 8} {