scripts: PARALLELMFLAGS is evil, rename

The reunification of the glibc/eglibc code paths exposed a nasty
bug in the glibc build: use of PARALLELMFLAGS breaks the build.

See the explanations in that bug report against FC6:
https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=212111

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Super-H specific configuration file

config ARCH_sh

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_USE_MMU

    select ARCH_SUPPORTS_BOTH_ENDIAN

    select ARCH_DEFAULT_LE

    help

      The Super-H architecture, as defined by:

        http://www.renesas.com/fmwk.jsp?cnt=superh_family_landing.jsp&fp=/products/mpumcu/superh_family/