https://bugs.webkit.org/show_bug.cgi?id=119445

Reviewed by Martin Robinson.

.: 

Instead of defining the ENABLE_JIT value through JSC_CPPFLAGS, the feature define is
set to be either enabled or disabled through the Autoconf header, based on the value
passed through the configuration flag. The 'auto' value is used as default, meaning
that the feature is enabled or disabled in the Platform.h header based on the platform
configuration (OS, architecture etc.).

* Source/autotools/FindDependencies.m4: Remove the JSC_CPPFLAGS definition.
* Source/autotools/ReadCommandLineArguments.m4: Change the default value to 'auto' instead
of 'autodetect', as used by other configuration options that take a similar approach to enabling
a specific feature.
* Source/autotools/SetupAutoconfHeader.m4: Set a strict value for the ENABLE_JIT define through
the Autoconf header if the feature was specifically enabled or disabled.

Source/JavaScriptCore: 

* GNUmakefile.am: Remove JSC_CPPFLAGS from the cpp flags for the JSC library.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153703 268f45cc-cd09-0410-ab3c-d52691b4dbfc