libc/glibc: fix installing syscall.h when installing start-files.

Reported-by: Rafael C <groups.r2@gmail.com>
Reported-by: Jérôme BARDON <bardon.pro@gmail.com>
Reported-by: Daniel Price <daniel.price@gmail.com>
[yann.morin.1998@free.fr: use a conditional approach, also suggested by Daniel]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

# Super-H specific configuration file

## 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:

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