optimize log facility for multi threading

- Shorten filenames
- Add log_printf with mutex locking to play nice with Serial and two
cores

cores/esp32/esp32-hal-misc.c

@@ -47,4 +47,18 @@ void delayMicroseconds(uint32_t us)
     }
 }
 
+//used by hal log
+const char * IRAM_ATTR pathToFileName(const char * path){
+    size_t i = 0;
+    size_t pos = 0;
+    char * p = (char *)path;
+    while(*p){
+        i++;
+        if(*p == '/' || *p == '\\'){
+            pos = i;
+        }
+        p++;
+    }
+    return path+pos;
+}