Use INLINE_ARM_FUNCTION in OFFLINE_ASM_GLOBAL_LABEL

We can get rid of an ifdef in LowLevelInterpreter by reusing logic
from InlineAsm.h. This also fixes ARM_TRADITIONAL when forced on when
thumb2 is available to the compiler.

Change-Id: Iac5ad22a4a41757fa03c3cbc2e8f68e44d085bae
Reviewed-by: Julien Brianceau <jbriance@cisco.com>
Reviewed-by: Michael Bruning <michael.bruning@digia.com>