ARM: #include <bits/arm_asm.h> where __USE_BX__ is used

The check for __USE_BX__ will be available in bits/arm_asm.h,
so the latter must be included wherever the former is used.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
Cc: Khem Raj <raj.khem@gmail.com>
Cc: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Cc: Carmelo AMOROSO <carmelo.amoroso@st.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

ldso/ldso/arm/dl-startup.h

@@ -7,6 +7,7 @@
  */
 
 #include <features.h>
+#include <bits/arm_asm.h>
 
 #if !defined(__thumb__)
 __asm__(

libc/sysdeps/linux/arm/sysdep.h

@@ -21,6 +21,7 @@
 #define _LINUX_ARM_SYSDEP_H 1
 
 #include <common/sysdep.h>
+#include <bits/arm_asm.h>
 
 #include <sys/syscall.h>
 /* For Linux we can use the system call table in the header file