tests/tcg/minilib: support %c format char

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

tests/tcg/minilib/printf.c

@@ -119,6 +119,9 @@ void ml_printf(const char *fmt, ...)
             str = va_arg(ap, char*);
             print_str(str);
             break;
+        case 'c':
+            __sys_outc(va_arg(ap, int));
+            break;
         case '%':
             __sys_outc(*fmt);
             break;