Revert "package/pkg-meson: handle b_pie"

This reverts commit a8a147f6.

That commit incorrectly made use of BR2_TOOLCHAIN_SUPPORTS_PIE, when it
should have been using BR2_PIC_PIE.

Besides, another attempt is pending, that unconditionally disables it as
it will be set by the toolchain wrapper already.

For both reasons, revert rather than switch over to BR2_PIC_PIE.

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