Fix duplicate __bx function definition in ARM backend

The ARM backend had two conflicting definitions of the __bx function,
causing compilation errors. This commit removes the incorrect duplicate
and keeps the proper BX (Branch and Exchange) instruction implementation.

The correct implementation uses: (cond << 28) | 0x012FFF10 | rm
which properly encodes the ARM BX instruction.

Author: jserv

src/arm.c

@@ -324,17 +324,17 @@ int __bl(arm_cond_t cond, int ofs)
     return arm_encode(cond, 176, 0, 0, 0) + (o & 16777215);
 }
 
-int __blx(arm_cond_t cond, arm_reg rd)
-{
-    return arm_encode(cond, 18, 15, 15, rd + 3888);
-}
-
 int __bx(arm_cond_t cond, arm_reg rm)
 {
     /* BX: Branch and Exchange */
     return (cond << 28) | 0x012FFF10 | rm;
 }
 
+int __blx(arm_cond_t cond, arm_reg rd)
+{
+    return arm_encode(cond, 18, 15, 15, rd + 3888);
+}
+
 int __mul(arm_cond_t cond, arm_reg rd, arm_reg r1, arm_reg r2)
 {
     return arm_encode(cond, 0, rd, 0, (r1 << 8) + 144 + r2);