Add optional versioned server file checker

If users have downloaded prebuilt server file, they may forget to update
the server file simply because they are all named "scrcpy-server". It is
already known to cause issues when server and client versions mismatch.
Let it check for "scrcpy-server-v<VERSION>" first (just as how it is
named in Github release page), then fall back to "scrcpy-server".

This mechanism is fully optional: users may still use the old unversioned
name "scrcpy-server"; or they can directly download server file from
release page without renaming it, and they will be notified to update
their server file because client cannot find either files (with the
correct version).

app/src/server.c

@@ -16,6 +16,8 @@
 #include "util/str.h"
 
 #define SC_SERVER_FILENAME "scrcpy-server"
+#define SC_SERVER_FILENAME_SUFFIX "-v" SCRCPY_VERSION
+#define SC_SERVER_FULL_FILENAME SC_SERVER_FILENAME SC_SERVER_FILENAME_SUFFIX
 
 #define SC_SERVER_PATH_DEFAULT PREFIX "/share/scrcpy/" SC_SERVER_FILENAME
 #define SC_DEVICE_SERVER_PATH "/data/local/tmp/scrcpy-server.jar"
@@ -53,11 +55,21 @@ get_server_path(void) {
         return NULL;
     }
 #else
-    char *server_path = sc_file_get_local_path(SC_SERVER_FILENAME);
+    char *server_path = sc_file_get_local_path(SC_SERVER_FULL_FILENAME);
     if (!server_path) {
-        LOGE("Could not get local file path, "
-             "using " SC_SERVER_FILENAME " from current directory");
-        return strdup(SC_SERVER_FILENAME);
+        LOGE("Could not get path of the executable file itself, "
+             "searching from current working directory");
+        server_path = strdup(SC_SERVER_FULL_FILENAME);
+        if (!server_path) {
+            LOG_OOM();
+            return NULL;
+        }
+    }
+
+    if (!sc_file_is_regular(server_path)) {
+        // versioned server file not found; give another try
+        server_path[strlen(server_path) -
+                    strlen(SC_SERVER_FILENAME_SUFFIX)] = '\0';
     }
 
     LOGD("Using server (portable): %s", server_path);