Minimize uses of lazy initialization by adding explicit initialization functions.

src/platform-posix.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
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@@ skipping 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef V8_PLATFORM_POSIX_H_
 #define V8_PLATFORM_POSIX_H_
 
 namespace v8 {
 namespace internal {
 
-// Used by platform implementation files during OS::PostSetUp() to initialize
-// the math functions.
-void MathSetup();
+// Used by platform implementation files during OS::PostSetUp().
+void POSIXPostSetUp();
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_POSIX_H_