RTX - fix missing header guards for Cortex-M4 (GCC ARM)

The HAL CM4 is valid only for FPU present. These guards were added
to mbed SDK, as there are targets Cortex-M4.

Author: 0xc0170

core/mbed-rtos/rtx/TARGET_CORTEX_M/TARGET_RTOS_M4_M7/TOOLCHAIN_GCC/HAL_CM4.S

@@ -220,8 +220,12 @@ SVC_Handler_Veneer:
 
 SVC_ContextSave:
         TST     LR,#0x10                /* is it extended frame? */
+#ifdef __FPU_PRESENT
         ITTE    EQ
         VSTMDBEQ R12!,{S16-S31}         /* yes, stack also VFP hi-regs */
+#else
+        ITE     EQ
+#endif
         MOVEQ   R0,#0x01                /* os_tsk->stack_frame val */
         MOVNE   R0,#0x00
         STRB    R0,[R1,#TCB_STACKF]     /* os_tsk.run->stack_frame = val */
@@ -239,10 +243,16 @@ SVC_ContextRestore:
         LDMIA   R12!,{R4-R11}           /* Restore New Context */
         LDRB    R0,[R2,#TCB_STACKF]     /* Stack Frame */
         CMP     R0,#0                   /* Basic/Extended Stack Frame */
+#ifdef __FPU_PRESENT
         ITEE    EQ
+#else
+        ITE     EQ
+#endif
         MVNEQ   LR,#~0xFFFFFFFD         /* set EXC_RETURN value */
         MVNNE   LR,#~0xFFFFFFED
+#ifdef __FPU_PRESENT
         VLDMIANE R12!,{S16-S31}         /* restore VFP hi-registers */
+#endif
         MSR     PSP,R12                 /* Write PSP */
 
 SVC_Exit:
@@ -313,8 +323,12 @@ Sys_Switch:
 
         MRS     R12,PSP                 /* Read PSP */
         TST     LR,#0x10                /* is it extended frame? */
+#ifdef __FPU_PRESENT
         ITTE    EQ
         VSTMDBEQ R12!,{S16-S31}         /* yes, stack also VFP hi-regs */
+#else
+        ITE     EQ
+#endif
         MOVEQ   R0,#0x01                /* os_tsk->stack_frame val */
         MOVNE   R0,#0x00
         STRB    R0,[R1,#TCB_STACKF]     /* os_tsk.run->stack_frame = val */
@@ -331,10 +345,16 @@ Sys_Switch:
         LDMIA   R12!,{R4-R11}           /* Restore New Context */
         LDRB    R0,[R2,#TCB_STACKF]     /* Stack Frame */
         CMP     R0,#0                   /* Basic/Extended Stack Frame */
+#ifdef __FPU_PRESENT
         ITEE    EQ
+#else
+        ITE     EQ
+#endif
         MVNEQ   LR,#~0xFFFFFFFD         /* set EXC_RETURN value */
         MVNNE   LR,#~0xFFFFFFED
+#ifdef __FPU_PRESENT
         VLDMIANE R12!,{S16-S31}         /* restore VFP hi-registers */
+#endif
         MSR     PSP,R12                 /* Write PSP */
 
 Sys_Exit: