Forward log and log level to custom bh_log callback (#3070)

Follow-up on #2907. The log level is needed in the host embedder to
better integrate with the embedder's logger.

Allow the developer to customize his bh_log callback with
`cmake -DWAMR_BH_LOG=<log_callback>`,
and update sample/basic to show the usage.

samples/basic/build.sh

@@ -21,7 +21,7 @@ echo "#####################build basic project"
 cd ${CURR_DIR}
 mkdir -p cmake_build
 cd cmake_build
-cmake .. -DCMAKE_BUILD_TYPE=Debug
+cmake .. -DCMAKE_BUILD_TYPE=Debug -DWAMR_BH_VPRINTF=my_vprintf -DWAMR_BH_LOG=my_log
 make -j ${nproc}
 if [ $? != 0 ];then
     echo "BUILD_FAIL basic exit as $?\n"

samples/basic/src/main.c

@@ -15,6 +15,30 @@ get_pow(int x, int y);
 int32_t
 calculate_native(int32_t n, int32_t func1, int32_t func2);
 
+void
+my_log(uint32 log_level, const char *file, int line, const char *fmt, ...)
+{
+    char buf[200];
+    snprintf(buf, 200,
+             log_level == WASM_LOG_LEVEL_VERBOSE ? "[WamrLogger - VERBOSE] %s"
+                                                 : "[WamrLogger] %s",
+             fmt);
+
+    va_list ap;
+    va_start(ap, fmt);
+    vprintf(buf, ap);
+    va_end(ap);
+}
+
+int
+my_vprintf(const char *format, va_list ap)
+{
+    /* Print in blue */
+    char buf[200];
+    snprintf(buf, 200, "\x1b[34m%s\x1b[0m", format);
+    return vprintf(buf, ap);
+}
+
 void
 print_usage(void)
 {
@@ -95,6 +119,7 @@ main(int argc, char *argv_main[])
         printf("Init runtime environment failed.\n");
         return -1;
     }
+    wasm_runtime_set_log_level(WASM_LOG_LEVEL_VERBOSE);
 
     buffer = bh_read_file_to_buffer(wasm_path, &buf_size);
 
@@ -103,7 +128,8 @@ main(int argc, char *argv_main[])
         goto fail;
     }
 
-    module = wasm_runtime_load(buffer, buf_size, error_buf, sizeof(error_buf));
+    module = wasm_runtime_load((uint8 *)buffer, buf_size, error_buf,
+                               sizeof(error_buf));
     if (!module) {
         printf("Load wasm module failed. error: %s\n", error_buf);
         goto fail;