[update] Removed C++ global constructor initialization, this method is not...

[update] Removed C++ global constructor initialization, this method is not used in GCC4.7 and later versions.

libcpu/arm/cortex-a/start_gcc.S

@@ -154,21 +154,6 @@ bss_loop:
     bl rt_hw_init_mmu_table
     bl rt_hw_mmu_init
 
-    /* call C++ constructors of global objects                          */
-    ldr     r0, =__ctors_start__
-    ldr     r1, =__ctors_end__
-
-ctor_loop:
-    cmp     r0, r1
-    beq     ctor_end
-    ldr     r2, [r0], #4
-    stmfd   sp!, {r0-r1}
-    mov     lr, pc
-    bx      r2
-    ldmfd   sp!, {r0-r1}
-    b       ctor_loop
-ctor_end:
-
     /* start RT-Thread Kernel */
     ldr     pc, _rtthread_startup
 _rtthread_startup: