This patch is analogous to r1502 submitted to the OpenImageIO project:   - move build and distribution definitions in the makefile so that     the 'platform' variable can be set inside a site specific     Makefile-bits.  We (SPI) find this handy so that developers can     have multiple builds for different linux platforms in one OSL     checkout directory.
This patch is analogous to r1502 submitted to the OpenImageIO project:
  - move build and distribution definitions in the makefile so that
    the 'platform' variable can be set inside a site specific
    Makefile-bits.  We (SPI) find this handy so that developers can
    have multiple builds for different linux platforms in one OSL
    checkout directory.


h3rb/openshadinglanguage,h3rb/openshadinglanguage,tectronics/openshadinglanguage,tectronics/openshadinglanguage,qdtk/openshadinglanguage,qdtk/openshadinglanguage,qdtk/openshadinglanguage,h3rb/openshadinglanguage,tectronics/openshadinglanguage,tectronics/openshadinglanguage,h3rb/openshadinglanguage,qdtk/openshadinglanguage