RISC-V: Allow rounding mode control for RVV floating-point add

RISC-V: Allow rounding mode control for RVV floating-point add

According to the doc as below, we need to support the rounding mode of
the RVV floating-point, both the static and dynamice frm.

https://github.com/riscv-non-isa/rvv-intrinsic-doc/pull/226

For tracking and development friendly, We will take some steps to support
all rounding modes for the RVV floating-point rounding modes.

1. Allow rounding mode control by one intrinsic (aka this patch), vfadd.
2. Support static rounding mode control by mode switch, like fixed-point.
3. Support dynamice round mode control by mode switch.
4. Support the rest floating-point instructions for frm.

Please *NOTE* this patch only allow the rounding mode control for the
vfadd intrinsic API, and the related frm will be coverred by step 2.

Signed-off-by: Pan Li <pan2.li@intel.com>
Co-Authored by: Juzhe-Zhong <juzhe.zhong@rivai.ai>

gcc/ChangeLog:

	* config/riscv/riscv-protos.h (enum floating_point_rounding_mode):
	Add macro for static frm min and max.
	* config/riscv/riscv-vector-builtins-bases.cc
	(class binop_frm): New class for floating-point with frm.
	(BASE): Add vfadd for frm.
	* config/riscv/riscv-vector-builtins-bases.h: Likewise.
	* config/riscv/riscv-vector-builtins-functions.def
	(vfadd_frm): Likewise.
	* config/riscv/riscv-vector-builtins-shapes.cc
	(struct alu_frm_def): New struct for alu with frm.
	(SHAPE): Add alu with frm.
	* config/riscv/riscv-vector-builtins-shapes.h: Likewise.
	* config/riscv/riscv-vector-builtins.cc
	(function_checker::report_out_of_range_and_not): New function
	for report out of range and not val.
	(function_checker::require_immediate_range_or): New function
	for checking in range or one val.
	* config/riscv/riscv-vector-builtins.h: Add function decl.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/float-point-frm-error.c: New test.
	* gcc.target/riscv/rvv/base/float-point-frm.c: New test.