Add "soname_version" parameter to common.gypi, v8.gyp, Makefile

Makefile

 # Copyright 2011 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
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 50 matching lines @@
 # liveobjectlist=on
 ifeq ($(liveobjectlist), on)
   GYPFLAGS += -Dv8_use_liveobjectlist=true
 endif
 # vfp3=off
 ifeq ($(vfp3), off)
   GYPFLAGS += -Dv8_can_use_vfp_instructions=false
 else
   GYPFLAGS += -Dv8_can_use_vfp_instructions=true
 endif
+# soname_version=1.2.3
+ifdef soname_version
+  GYPFLAGS += -Dsoname_version=$(soname_version)
+endif
 
 # ----------------- available targets: --------------------
 # - "dependencies": pulls in external dependencies (currently: GYP)
 # - any arch listed in ARCHES (see below)
 # - any mode listed in MODES
 # - every combination <arch>.<mode>, e.g. "ia32.release"
 # - any of the above with .check appended, e.g. "ia32.release.check"
 # - default (no target specified): build all ARCHES and MODES
 # - "check": build all targets and run all tests
 # - "<arch>.clean" for any <arch> in ARCHES
@@ skipping 88 matching lines @@
             else mv $(ENVFILE).new $(ENVFILE); fi
 
 # Stores current GYPFLAGS in a file.
 $(ENVFILE).new:
         @mkdir -p $(OUTDIR); echo "GYPFLAGS=$(GYPFLAGS)" > $(ENVFILE).new;
 
 # Dependencies.
 dependencies:
         svn checkout --force http://gyp.googlecode.com/svn/trunk build/gyp \
             --revision 1026