nodejs6: fix build on older systems

allows build on < 10.7

devel/nodejs6/Portfile

@@ -49,6 +49,11 @@ configure.python ${prefix}/bin/python2.7
 patchfiles              patch-common.gypi.diff \
                         patch-tools-gyp-pylib-gyp-generator-make.py.diff
 
+if { ${configure.cxx_stdlib} eq "libc++" } {
+    # libc++ headers don't put this in <tr1/>
+    patchfiles-append   patch-nodejs6-old-tr1-calls.diff
+}
+
 post-patch {
     foreach f [concat ${worksrcpath}/configure \
                    ${worksrcpath}/tools/gyp/gyp \
@@ -65,6 +70,12 @@ post-patch {
     reinplace "s|/usr/bin/env node|${prefix}/bin/node|" ${worksrcpath}/tools/doc/node_modules/marked/bin/marked
 }
 
+# We'll use the system libuv instead, as it is fixed for older systems
+if { ${os.platform} eq "darwin" && ${os.major} < 11 } {
+    depends_lib-append    path:lib/libuv.dylib:libuv
+    configure.args-append --shared-libuv
+}
+
 configure.args-append   --without-npm
 configure.args-append   --with-intl=system-icu
 configure.args-append   --shared-openssl
@@ -205,13 +216,6 @@ destroot {
         ${docdir}
 }
 
-if {${os.major} < 11} {
-    pre-fetch {
-        ui_error "${name} ${version} requires Mac OS X 10.7 or greater."
-        return -code error "incompatible Mac OS X version"
-    }
-}
-
 livecheck.url       ${homepage}dist/
 livecheck.type      regex
 livecheck.regex     {v(6\.\d+\.\d+)}

devel/nodejs6/files/patch-nodejs6-old-tr1-calls.diff

@@ -0,0 +1,19 @@
+--- src/util.h.orig	2019-04-21 18:08:50.000000000 -0700
++++ src/util.h	2019-04-21 18:10:53.000000000 -0700
+@@ -12,16 +12,7 @@
+ #include <stdlib.h>
+ #include <string.h>
+
+-// OSX 10.9 defaults to libc++ which provides a C++11 <type_traits> header.
+-#if defined(__APPLE__) && __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 1090
+-#define USE_TR1_TYPE_TRAITS
+-#endif
+-
+-#ifdef USE_TR1_TYPE_TRAITS
+-#include <tr1/type_traits>  // NOLINT(build/c++tr1)
+-#else
+ #include <type_traits>  // std::remove_reference
+-#endif
+
+ namespace node {
+