Enable GP Relaxation optimization

- Enabled `-mrelax` compiler flag in CMake configuration.
- Updated entry.s to correctly initialize the Global Pointer (`gp`) using
the `__global_pointer$` symbol.
- Verified that `gp` is treated as a constant and no longer saved/restored
during context switches, improving performance.

Author: Winstonllllai

cmake/riscv32_gnu.cmake

@@ -4,7 +4,7 @@ set(CMAKE_SYSTEM_PROCESSOR risc-v32)
 
 set(THREADX_ARCH "risc-v32")
 set(THREADX_TOOLCHAIN "gnu")
-set(ARCH_FLAGS "-g -march=rv32gc -mabi=ilp32d -mcmodel=medany")
+set(ARCH_FLAGS "-g -march=rv32gc -mabi=ilp32d -mcmodel=medany -mrelax")
 set(CFLAGS "${ARCH_FLAGS}")
 set(ASFLAGS "${ARCH_FLAGS}")
 set(LDFLAGS "${ARCH_FLAGS}")

ports/risc-v32/gnu/example_build/qemu_virt/entry.s

@@ -11,7 +11,10 @@ _start:
 	bne  t0, zero, 1f
 	li x1, 0
 	li x2, 0
-	li x3, 0
+.option push
+.option norelax
+	la gp, __global_pointer$
+.option pop
 	li x4, 0
 	li x5, 0
 	li x6, 0