RISC-V: Make `no_aliases' bool

This commit changes the type of `no_aliases' from int to bool to
prepare adding more boolean options (bool is widely used on riscv-dis.c
already).

opcodes/ChangeLog:

	* riscv-dis.c (no_aliases) Change type from int to bool.
	(set_default_riscv_dis_options): Use a boolean literal.
	(parse_riscv_dis_option_without_args): Likewise.

opcodes/riscv-dis.c

@@ -65,7 +65,7 @@ static const char * const *riscv_gpr_names;
 static const char * const *riscv_fpr_names;
 
 /* If set, disassemble as most general instruction.  */
-static int no_aliases;
+static bool no_aliases = false;
 
 /* If set, disassemble with numeric registers.  */
 static bool is_numeric = false;
@@ -96,7 +96,7 @@ init_riscv_dis_state_for_arch_and_options (void)
 static void
 set_default_riscv_dis_options (void)
 {
-  no_aliases = 0;
+  no_aliases = false;
   is_numeric = false;
 }
 
@@ -138,7 +138,7 @@ static bool
 parse_riscv_dis_option_without_args (const char *option)
 {
   if (strcmp (option, "no-aliases") == 0)
-    no_aliases = 1;
+    no_aliases = true;
   else if (strcmp (option, "numeric") == 0)
     is_numeric = true;
   else