Add bh_print_proc_mem() to dump memory info of current process (#1734)

Only support Posix platforms currently, read memory consumption info from
file "/proc/self/status".

core/shared/platform/common/freertos/freertos_malloc.c

@@ -20,3 +20,9 @@ os_realloc(void *ptr, unsigned size)
 void
 os_free(void *ptr)
 {}
+
+int
+os_dumps_proc_mem_info(char *out, unsigned int size)
+{
+    return -1;
+}

core/shared/platform/common/posix/posix_malloc.c

@@ -22,3 +22,51 @@ os_free(void *ptr)
 {
     free(ptr);
 }
+
+int
+os_dumps_proc_mem_info(char *out, unsigned int size)
+{
+    int ret = -1;
+    FILE *f;
+    char line[128] = { 0 };
+    unsigned int out_idx = 0;
+
+    if (!out || !size)
+        goto quit;
+
+    f = fopen("/proc/self/status", "r");
+    if (!f) {
+        perror("fopen failed: ");
+        goto quit;
+    }
+
+    memset(out, 0, size);
+
+    while (fgets(line, sizeof(line), f)) {
+#if WASM_ENABLE_MEMORY_PROFILING != 0
+        if (strncmp(line, "Vm", 2) == 0 || strncmp(line, "Rss", 3) == 0) {
+#else
+        if (strncmp(line, "VmRSS", 5) == 0
+            || strncmp(line, "RssAnon", 7) == 0) {
+#endif
+            size_t line_len = strlen(line);
+            if (line_len >= size - 1 - out_idx)
+                goto close_file;
+
+            /* copying without null-terminated byte */
+            memcpy(out + out_idx, line, line_len);
+            out_idx += line_len;
+        }
+    }
+
+    if (ferror(f)) {
+        perror("fgets failed: ");
+        goto close_file;
+    }
+
+    ret = 0;
+close_file:
+    fclose(f);
+quit:
+    return ret;
+}