lib: newlib: Remove internal _sbrk lock

This commit removes the lock inside the newlib internal `_sbrk`
function, which is called by `malloc` when additional heap memory is
needed.

This lock is no longer required because any calls to the `malloc`
function are synchronised by the `__malloc_lock` and `__malloc_unlock`
functions.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
1 file changed