yasm: add support for targeting iOS (at least simulator) by copying mac->ios

third_party/yasm/README.chromium

 Name: yasm
 URL: http://www.tortall.net/projects/yasm/
 Version: 1.2.0
 License: 2-clause or 3-clause BSD licensed, with the exception of bitvect, which is triple-licensed under the Artistic license, GPL, and LGPL
 License File: source/patched-yasm/COPYING
 License Android Compatible: yes
 Security Critical: no
 
 With these patches merged:
 * https://github.com/yasm/yasm/commit/a2cbb10ee1b90b73647667ac849c74d65761d412
@@ skipping 19 matching lines @@
   3) Next, capture all the output from a build of yasm.  We will use the build
      log as a reference for making the yasm.gyp file.
 
        make yasm > yasm_build_log 2> yasm_build_err
 
   4) Check yasm_build_err to see if there are any anomalies beyond yasm's
      compiler warnings.
 
   5) Grab the generated Makefile, libyasm-stdint.h, config.h, and put into
      the correct platform location. For android platform, copy the files
-     generated for linux.
+     generated for linux.  For ios, copy the files from mac.
 
        src/third_party/yasm/source/config/[platform]
 
      While we do not directly use the "Makefile" to build, it is needed by
      the "genmodule" subprogram as input for creating the available modules
      list.
 
   6) Make sure all the subprograms are represented in yasm.gyp.
 
        grep '^gcc' yasm_build_log  |
@@ skipping 77 matching lines @@
      Yasm uses python scripts to generate the assembly code description
      files in C++. Make sure to get these put into the gyp file properly as
      well.  An example is gen_x86_insn.py for x86 assembly.
 
      Note that at least the gen_x86_insn.py script suffers from the same
      problem as genmacro in that it outputs to the current directory by
      default.  The yasm.gyp build patches this file before invoking it to
      allow specifying an output directory.
 
  10) If all that's is finished, attempt to build....and cross your fingers.