aarch64: Fix ICE happening in SET_TYPE_VECTOR_SUBPARTS with libgccjit

aarch64: Fix ICE happening in SET_TYPE_VECTOR_SUBPARTS with libgccjit

The structure aarch64_simd_type_info was split in 2 because we do not
want to reset the static members of aarch64_simd_type_info to their
default value. We only want the tree types to be GC-ed. This is
necessary for libgccjit which can run multiple times in the same
process. If the static values were GC-ed, the second run would
ICE/segfault because of their invalid value.

The following test suites passed for this patch:

 * The aarch64 tests.
 * The aarch64 regression tests.

The number of failures of the jit tests on aarch64 lowered from +100 to
~7.

gcc/ChangeLog:
	PR target/117923
	* config/aarch64/aarch64-builtins.cc: Remove GTY marker on aarch64_simd_types,
	aarch64_simd_types_trees (new variable), rename aarch64_simd_types to
	aarch64_simd_types_trees.
	* config/aarch64/aarch64-builtins.h: Remove GTY marker on aarch64_simd_types,
	aarch64_simd_types_trees (new variable).
	* config/aarch64/aarch64-sve-builtins-shapes.cc: Rename aarch64_simd_types to
	aarch64_simd_types_trees.
	* config/aarch64/aarch64-sve-builtins.cc: Rename aarch64_simd_types to
	aarch64_simd_types_trees.