[ARM/FDPIC v6 12/24] [ARM] FDPIC: Restore r9 after we call __aeabi_read_tp

[ARM/FDPIC v6 12/24] [ARM] FDPIC: Restore r9 after we call __aeabi_read_tp

We call __aeabi_read_tp() to get the thread pointer. Since this is a
function call, we have to restore the FDPIC register afterwards.

2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné <mickael.guene@st.com>

	gcc/
	* config/arm/arm.c (arm_load_tp): Add FDPIC support.
	* config/arm/arm.md (FDPIC_REGNUM): New constant.
	(load_tp_soft_fdpic): New pattern.
	(load_tp_soft): Disable in FDPIC mode.

Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
From-SVN: r275574