* src/port.h: use const poiters to strings

* src/port.h: use const poiters to strings
* src/SDCCargs.h: declared getStringArg() and getIntArg()
* src/pic16/main.c: include SDCCargs.h
* src/SDCCglobl.h: code_seg and const_seg are not pointers to
  const char, since the strings are dynamically allocated
* src/SDCCmain.c: options.code_seg and options.const_seg are
  dynamically allocated; check port specific command line options
  before the general ones
* src/z80/main.c: fixed bug #1631895: codeseg/constseg #pragma fail

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@4758 4a8a32a2-be11-0410-ad9d-d568d2c75423