contrib: fix gcc test suite on system without echo -e

Fix the use of quotes in contrib/gcc-test-suite/Makefile to solve the
problem where board.exp is incorrectly generated on some build systems
where 'echo -e' is not handled correctly.

Signed-off-by: Andy Gibbs <andyg1001@hotmail.co.uk>
[Yann E. MORIN: fix space damage, pretty-up the stuff]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 syntax: glob

 # Generated files

 Makefile

 ct-ng

 docs/ct-ng.1

 docs/ct-ng.1.gz

 paths.mk

 scripts/crosstool-NG.sh

 scripts/saveSample.sh

 scripts/showTuple.sh

 kconfig/conf

 kconfig/mconf

 kconfig/**.o

 kconfig/**.dep

 config.gen/

 .config

 # Temporaries

 .*.swp

 log.*

 .config.old

 # This is the place where toolchains are built

 .build/

 # .. and the legacy location

 targets/