ScGlobal::FindUnquoted
  - return -1 instead of STRING_NOTFOUND
  - change return type from xub_StrLen to sal_Int32
  - remove last two parameters because noone was using them

ScCompiler::GetDocTabPos
  - return -1 instead of STRING_NOTFOUND
  - change return type from xub_StrLen to sal_Int32

inputhdl.cxx/lcl_MatchParenthesis
  - return -1 instead of STRING_NOTFOUND
  - change return type from xub_StrLen to sal_Int32
  - make function static, no-one outside this module is using it

Change-Id: I141ab082db180ff2da5a7ca6813cd3607b9ea7f7