cc/gcc: remove --enable-symver option

That option is coming from the original crosstool, and is not entirely
understand here.

Moreover, it breaks with newer gcc-s: 4.6.1 now breaks while configuring
libjava (and probably some other libs as well, untested).

There is an related bug report to the gcc BZ:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49555

If need be, the old behavior can be restored with:
CC_CORE_EXTRA_CONFIG_ARRAY="--enable-symver=gnu"
CC_EXTRA_CONFIG_ARRAY="--enable-symver=gnu"

Reported-by: Bryan Hundven <bryanhundven@gmail.com>
Reviewed-by: Bryan Hundven <bryanhundven@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from b24ead1a59472195f5b2071ff70664c36fa21c3f)

 # powerpc specific configuration file

 config ARCH_POWERPC_SPE

     bool

     prompt "Enable SPE support"

     default n

     help

       Add support for the Signal Processing Engine.  This will set up

       the toolchain so that it supports the SPE ABI extensions. This

       mainly targets Freescale e500 processors.

       Setting this option will append "spe" to the end of your target

       tuple name (e.g., powerpc-e500v2-linux-gnuspe) so that the gcc

       configure/build system will know to include SPE ABI support.

       It will also automatically add "-mabi=spe -mspe" to your

       TARGET_CFLAGS, and "--enable-e500_double" to your CC_EXTRA_CONFIG,

       so you do not need to explicitly add them.