libc/glibc: do not consume parameters when parsing them

Currently, there are two constructs used to parse arguments in
glibc backends, one that consumes args as they are parsed, and
one that does not.

Always use the construct that does not eat args as they are parsed.

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

 # Default test suite configuration

 # Default DejaGnu configuration

 DG_TOOLNAME = gcc

 DG_TARGET_HOSTNAME = 127.0.0.1

 DG_TARGET_USERNAME = root

 # Default tests

 DG_C_TESTS = 

 DG_CPP_TESTS =