[EFL] Make plugin process debugging easier (PLUGIN_PROCESS_COMMAND_PREFIX)

[EFL] Make plugin process debugging easier (PLUGIN_PROCESS_COMMAND_PREFIX)
https://bugs.webkit.org/show_bug.cgi?id=99297

Patch by Jussi Kukkonen <jussi.kukkonen@intel.com> on 2012-10-23
Reviewed by Kenneth Rohde Christiansen.

Add support for PLUGIN_PROCESS_COMMAND_PREFIX environment variable, to allow easier
plugin debugging with e.g.:
$ PLUGIN_PROCESS_COMMAND_PREFIX="xterm gdb --args" MiniBrowser

* UIProcess/Plugins/unix/PluginProcessProxyUnix.cpp:
(WebKit::PluginProcessProxy::platformInitializeLaunchOptions):
(WebKit):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@132209 268f45cc-cd09-0410-ab3c-d52691b4dbfc