Add Raspberry Pi compile hints.

README_linux_compile.md

@@ -13,6 +13,12 @@ the following command(s) may still be needed:
 sudo apt-get install build-essential pkg-config libasound2-dev libcdio-dev libsdl1.2-dev libsdl-net1.2-dev libsndfile1-dev zlib1g-dev  
 ```
 
+#### Raspberry Pi Additional Dependencies
+
+```
+sudo apt-get install libsdl2-2.0-0 libsdl2-dev
+```
+
 ### Compile Commands
 
 Mednafen's build process makes use of 'configure' in order to set up environment-specific options in preparation
@@ -36,3 +42,8 @@ It is possible that the sound device may not be properly identified by Mednafen;
 Mednafen documentation has some hints here:
 [https://mednafen.github.io/documentation/#Section_troubleshooting_nosoundlinux](https://mednafen.github.io/documentation/#Section_troubleshooting_nosoundlinux)
 
+On Raspberry Pi, you will almost certainly need to update the sound.device in the Mednafen settings as specified in
+https://mednafen.github.io/releases/ :
+```
+sound.device sexyal-literal-default
+```