util/log: improve logger_android

Avoid __android_log_vprint which can truncate messages.  Also add
MESA_LOG=wait to lower the chance of logger_android dropping messages.

Reviewed-by: Emma Anholt <emma@anholt.net>
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21454>

src/android_stub/log_stub.cpp

@@ -2,6 +2,11 @@
 
 extern "C" {
 
+int __android_log_write(int prio, const char* tag, const char* text)
+{
+   return 0;
+}
+
 int __android_log_print(int prio, const char* tag, const char* fmt, ...)
 {
    return 0;