Build fix for mbedk64f target

[robertsipka]

JerryScript-DCO-1.0-Signed-off-by: Robert Sipka rsipka.uszeged@partner.samsung.com

[LaszloLango]

LGTM

[zherczeg]

Why this is a problem?

http://www.cplusplus.com/reference/cstdio/putchar/

putchar should accept int argument.

[robertsipka]

@zherczeg : A conversion error (conversion to 'unsigned char' from 'int' may alter its value) occurs when I tried to build to mbedk64f target with enabled USE_COMPILER_DEFAULT_LIBC.
It's the default value of this option (hard-coded in the Makefile.mbedk64f), and the same happens when I compile to another target with the following options:
USE_COMPILER_DEFAULT_LIBC=YES make release.mcu_stm32f3-cp
As I assume this is a compiler-specific error, and I dared to casting int to unsigned char because the value is internally converted to an unsigned char anyway.

[zherczeg]

Btw could we make jerry_port_putchar to accept unsigned char? Is it frequently used?

[robertsipka]

No, it's very rarely used, but we couldn't get away with the cast, for example the following line :
jerry_port_putchar (ecma_char)
will be reported the same error, because the type of the variable is an ecma_char_t which is a typedef to uint16_t.
(In case of this kind of build configuration)

[zherczeg]

LGTM

[robertsipka]

Rebased with master.