Add nacl_sdk gyp meta-target.

build/build_nexe.py

Index: build/build_nexe.py
diff --git a/build/build_nexe.py b/build/build_nexe.py
index 7d9ac12482923d1a961927034ad0f8dd9d9fa0c8..f754fe788ee1ba9f897f4d17a65cda7fe0879f00 100644
--- a/build/build_nexe.py
+++ b/build/build_nexe.py
@@ -209,6 +209,10 @@ class Builder(object):
     options = ArgToList(options)
     if self.toolname in ['glibc', 'newlib'] and self.mainarch == 'x86':
       options += ['-B' + self.toollib]
+    if self.outtype == 'nso':
+      options += ['-Wl,-rpath-link,' + name for name in self.lib_paths]
+      options += ['-shared']
+      options += ['-Wl,-soname,' + os.path.basename(self.name)]
     self.link_options = options + ['-L' + name for name in self.lib_paths]
 
   def BuildArchiveOptions(self):
@@ -355,7 +359,7 @@ class Builder(object):
 
     Link or Archive the final output file, from the compiled sources.
     """
-    if self.outtype == 'nexe':
+    if self.outtype in ['nexe', 'nso']:
       out = self.Link(srcs)
       if self.strip_debug:
         self.Strip(out)