RISC-V: Bugfix function target attribute pollution

RISC-V: Bugfix function target attribute pollution

This patch depends on below ICE fix.

https://gcc.gnu.org/pipermail/gcc-patches/2024-March/647915.html

The function target attribute should be on a per-function basis.
For example, we have 3 function as below:

void test_1 () {}

void __attribute__((target("arch=+v"))) test_2 () {}

void __attribute__((target("arch=+zfh"))) test_3 () {}

void test_4 () {}

The scope of the target attribute should not extend the function body.
Aka, test_3 cannot have the 'v' extension, as well as the test_4
cannot have both the 'v' and 'zfh' extension.

Unfortunately, for now the test_4 is able to leverage the 'v' and
the 'zfh' extension which is incorrect.  This patch would like to
fix the sticking attribute by introduce the commandline subset_list.
When parse_arch, we always clone from the cmdline_subset_list instead
of the current_subset_list.

Meanwhile, we correct the print information about arch like below.

.option arch, rv64i2p1_m2p0_a2p1_f2p2_d2p2_c2p0_zicsr2p0_zifencei2p0_zbb1p0

The riscv_declare_function_name hook is always after the hook
riscv_process_target_attr.  Thus, we introduce one hash_map to record
the 1:1 mapping from fndel to its' subset_list in advance.  And later
the riscv_declare_function_name is able to get the right information
about the arch.

Below test are passed for this patch
* The riscv fully regression test.

	PR target/114352

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc (struct riscv_func_target_info):
	New struct for func decl and target name.
	(struct riscv_func_target_hasher): New hasher for hash table mapping
	from the fn_decl to fn_target_name.
	(riscv_func_decl_hash): New func to compute the hash for fn_decl.
	(riscv_func_target_hasher::hash): New func to impl hash interface.
	(riscv_func_target_hasher::equal): New func to impl equal interface.
	(riscv_cmdline_subset_list): New static var for cmdline subset list.
	(riscv_func_target_table_lazy_init): New func to lazy init the func
	target hash table.
	(riscv_func_target_get): New func to get target name from hash table.
	(riscv_func_target_put): New func to put target name into hash table.
	(riscv_func_target_remove_and_destory): New func to remove target
	info from the hash table and destory it.
	(riscv_parse_arch_string): Set the static var cmdline_subset_list.
	* config/riscv/riscv-subset.h (riscv_cmdline_subset_list): New static
	var for cmdline subset list.
	(riscv_func_target_get): New func decl.
	(riscv_func_target_put): Ditto.
	(riscv_func_target_remove_and_destory): Ditto.
	* config/riscv/riscv-target-attr.cc (riscv_target_attr_parser::parse_arch):
	Take cmdline_subset_list instead of current_subset_list when clone.
	(riscv_process_target_attr): Record the func target info to hash table.
	(riscv_option_valid_attribute_p): Add new arg tree fndel.
	* config/riscv/riscv.cc (riscv_declare_function_name): Consume the
	func target info and print the arch message.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/pr114352-3.c: New test.

Signed-off-by: Pan Li <pan2.li@intel.com>