osx: support GCC 4.6+ and Clang 3.3+

* autotools was set for clang++ only on OSX. Revert that.
Merge pull request #1 from guitorri/fix_gcc_clang_osx

osx: support GCC 4.6+ and Clang 3.3+
bug: spicefile QProcess unkwon signals

* QProcess migrated but signals were left behind. Slots not triggered
  and the qucsconv was not being read.
fix: Warning: QLayout: Attempting to add QLayout "" to DiagramDialog "", which already has a layout

* removed commented and ported code
bug: spicefile preprocessor QProcess unknown signals

* QProcess migrated but signals were left behind
* old signals, will not trigger slots. \todo test preprocessor