arm: Call thumb1_gen_const_int from thumb1_movsi_insn

arm: Call thumb1_gen_const_int from thumb1_movsi_insn

thumb1_movsi_insn used the same algorithm to build a constant in asm
than thumb1_gen_const_int_1 does in RTL. Since the previous patch added
support for asm generation in thumb1_gen_const_int_1, this patch calls
it from thumb1_movsi_insn to avoid duplication.

We need to introduce a new proxy function, thumb1_gen_const_int_print
to select the right template.

This patch also adds a new testcase as the updated alternative is only
used by thumb-1 processors that also support movt/movw.

2020-11-02  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	* config/arm/thumb1.md (thumb1_movsi_insn): Call
	thumb1_gen_const_int_print.
	* config/arm/arm-protos.h (thumb1_gen_const_int_print): Add
	prototype.
	* config/arm/arm.c (thumb1_gen_const_int_print): New.

	gcc/testsuite/
	* gcc.target/arm/pure-code/no-literal-pool-m23.c: New.