spinlock: move constructor out of x86 header file

spinlock: move constructor out of x86 header file

Having constructor function in the header file is generally
a bad idea, as it will eventually be implanted to 3rd party
library.

In this case it causes linking issues with 3rd party libraries
when an application is not linked to dpdk, due to missing
symbol called by constructor.

Fixes: ba7468997ea6 ("spinlock: add HTM lock elision for x86")
Signed-off-by: Damjan Marion <damarion@cisco.com>
Reviewed-by: Jan Viktorin <viktorin@rehivetech.com>
Signed-off-by: Thomas Monjalon <thomas.monjalon@6wind.com>