Fix the toolchain setup script to cope with macOS SDKs that aren't ve…

…rsion 10.x

README.md

@@ -22,9 +22,10 @@ freely). It has been tested with and should work with Xcode versions 7,
 8, 9 and 10.
 Older versions of Xcode can be downloaded from [Apple](https://developer.apple.com/download/more/).
 
-Using an Xcode 11 bundle works somewhat; building with generic build
+Using an Xcode 11 or 12 bundle works somewhat; building with generic build
 systems works fine, but there's a few known issues if building Xcode
 project files with xcbuild, for other than the simplest project files.
+(For Xcode 12, xcbuild doesn't seem to work at all.)
 
 The Xcode bundle can be stripped down to more manageable sizes for use
 with this cross compilation setup, since very little of the bundle

setup-toolchain.sh

@@ -77,7 +77,7 @@ fi
 if [ -z "\$SYSROOT_SET" ]; then
 	# Is there a better way to find the default sdk?
 	SDKS=\$DEVELOPER_DIR/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs
-	SDK=\$SDKS/\$(ls \$SDKS | grep MacOSX10 | head -1)
+	SDK=\$SDKS/\$(ls \$SDKS | grep MacOSX1 | head -1)
 	ARGS+=(-isysroot \$SDK)
 fi
 export PATH=$CCTOOLS/bin:\$PATH