buildroot

toolchain/wrapper: use the {str, len} tuples for the unsafe paths

In 61cb120 (toolchain/wrapper: extend paranoid check to -isystem), we
introduced a {str,len} tuple to check the various arguments pased to
gcc, to avoid hard-coding an ever-growing, long list of those args
directly in the condition check.

Now, we're left with a long list of unsafe paths, somehow hidden within
the code, which can use the same mechanism we use for arguments.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>