Fix for mame SDL Framework linking error

SDL_Mame_Fixup

I saw this failure with mame0211b on macOS

% ./mame64
dyld: Library not loaded: @rpath/SDL2.framework/Versions/A/SDL2
  Referenced from: /Users/stephenfitch/bin/mame0211b_macOS/./mame64
  Reason: image not found
[1]    34274 abort      ./mame64

% otool -L mame64
mame64:
 /System/Library/Frameworks/QuartzCore.framework/Versions/A/QuartzCore (compatibility version 1.2.0, current version 1.11.0)
 /System/Library/Frameworks/OpenGL.framework/Versions/A/OpenGL (compatibility version 1.0.0, current version 1.0.0)
 /System/Library/Frameworks/Metal.framework/Versions/A/Metal (compatibility version 1.0.0, current version 161.7.1)
 /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.250.1)
 /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 23.0.0)
 @rpath/SDL2.framework/Versions/A/SDL2 (compatibility version 1.0.0, current version 10.0.0)
 /System/Library/Frameworks/CoreMIDI.framework/Versions/A/CoreMIDI (compatibility version 1.0.0, current version 69.0.0)
 /System/Library/Frameworks/AudioUnit.framework/Versions/A/AudioUnit (compatibility version 1.0.0, current version 1.0.0)
 /System/Library/Frameworks/AudioToolbox.framework/Versions/A/AudioToolbox (compatibility version 1.0.0, current version 492.0.0)
 /System/Library/Frameworks/CoreAudio.framework/Versions/A/CoreAudio (compatibility version 1.0.0, current version 1.0.0)
 /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (compatibility version 1.0.0, current version 944.3.0)
 /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 400.9.4)
 /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit (compatibility version 45.0.0, current version 1671.40.118)
 /System/Library/Frameworks/ApplicationServices.framework/Versions/A/ApplicationServices (compatibility version 1.0.0, current version 50.1.0)
 /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1570.15.0)
 /System/Library/Frameworks/CoreGraphics.framework/Versions/A/CoreGraphics (compatibility version 64.0.0, current version 1251.12.0)
 /System/Library/Frameworks/CoreText.framework/Versions/A/CoreText (compatibility version 1.0.0, current version 1.0.0)
 /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation (compatibility version 300.0.0, current version 1570.15.0)
 /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)

Fixed :-) using install_name_tool 

% install_name_tool -change @rpath/SDL2.framework/Versions/A/SDL2 /usr/local/Cellar/sdl2/2.0.9_1/lib/libSDL2.dylib ./mame64