Fix sample littlevgl/gui build issues on zephyr platform (#588)

Fix sample littlevgl/guil build issues on zephyr platform, modify code of zephyr platform by adding some macros to control some apis to fit different zephyr version, and align to zephyr-v2.3.0 for sample littlevgl/gui as the latest zephyr version (>=v2.4.0) requires that the thread stack for the thread to create must be defined by macro but not allocating stack memory dynamically.

Signed-off-by: Wenyong Huang <wenyong.huang@intel.com>

core/shared/platform/zephyr/platform_internal.h

@@ -9,7 +9,12 @@
 #include <autoconf.h>
 #include <zephyr.h>
 #include <kernel.h>
+#include <version.h>
+#if KERNEL_VERSION_NUMBER >= 0x020200 /* version 2.2.0 */
 #include <sys/printk.h>
+#else
+#include <misc/printk.h>
+#endif
 #include <inttypes.h>
 #include <stdarg.h>
 #include <ctype.h>
@@ -53,7 +58,13 @@ typedef struct korp_cond {
     os_thread_wait_list thread_wait_list;
 } korp_cond;
 
-#define os_printf printf
+#ifndef Z_TIMEOUT_MS
+#define Z_TIMEOUT_MS(ms) ms
+#endif
+
+void abort(void);
+size_t strspn(const char *s, const char *accept);
+size_t strcspn(const char *s, const char *reject);
 
 /* math functions which are not provided by os */
 double sqrt(double x);

core/shared/platform/zephyr/zephyr_platform.c

@@ -101,7 +101,6 @@ char_out(int c, void *ctx)
     out_ctx->count++;
     return _stdout_hook_iwasm(c);
 }
-#endif
 
 int
 os_vprintf(const char *fmt, va_list ap)
@@ -115,6 +114,59 @@ os_vprintf(const char *fmt, va_list ap)
     return 0;
 #endif
 }
+#endif
+
+int
+os_printf(const char *format, ...)
+{
+    int ret = 0;
+    va_list ap;
+
+    va_start(ap, format);
+#ifndef BH_VPRINTF
+    ret += vprintf(format, ap);
+#else
+    ret += BH_VPRINTF(format, ap);
+#endif
+    va_end(ap);
+
+    return ret;
+}
+
+int
+os_vprintf(const char *format, va_list ap)
+{
+#ifndef BH_VPRINTF
+    return vprintf(format, ap);
+#else
+    return BH_VPRINTF(format, ap);
+#endif
+}
+
+#if KERNEL_VERSION_NUMBER <= 0x020400 /* version 2.4.0 */
+void
+abort(void)
+{
+    int i = 0;
+    os_printf("%d\n", 1 / i);
+}
+#endif
+
+#if KERNEL_VERSION_NUMBER <= 0x010E01 /* version 1.14.1 */
+size_t
+strspn(const char *s, const char *accept)
+{
+    os_printf("## unimplemented function %s called", __FUNCTION__);
+    return 0;
+}
+
+size_t
+strcspn(const char *s, const char *reject)
+{
+    os_printf("## unimplemented function %s called", __FUNCTION__);
+    return 0;
+}
+#endif
 
 void *
 os_mmap(void *hint, size_t size, int prot, int flags)

core/shared/platform/zephyr/zephyr_thread.c

@@ -353,7 +353,12 @@ int os_mutex_lock(korp_mutex *mutex)
 
 int os_mutex_unlock(korp_mutex *mutex)
 {
+#if KERNEL_VERSION_NUMBER >= 0x020200 /* version 2.2.0 */
     return k_mutex_unlock(mutex);
+#else
+    k_mutex_unlock(mutex);
+    return 0;
+#endif
 }
 
 int os_cond_init(korp_cond *cond)