aarch64: Fix an oversight in aarch64_evpc_reencode

aarch64: Fix an oversight in aarch64_evpc_reencode

Some fields (e.g., zero_op0_p and zero_op1_p) of the struct "newd" may be left
uninitialized in aarch64_evpc_reencode. This can cause reading of uninitialized
data. I found this oversight when testing my patches on and/fmov
optimizations. This patch fixes the bug by zero initializing the struct.

Pushed as obvious after bootstrap/test on aarch64-linux-gnu.

gcc/ChangeLog:

	* config/aarch64/aarch64.cc (aarch64_evpc_reencode): Zero initialize
	newd.