Revert "SL-13082 Declare macOS SDK version to be 10.12 instead of 10.15"

This reverts commit 7d4b1c01.
Until the TC mac build nodes update.

doc/contributions.txt

@@ -1462,7 +1462,6 @@ Tonya Souther
 	BUG-3875
 	BUG-3968
 	OPEN-345
-	SL-13082
 Torben Trautman
 TouchaHoney Perhaps
 TraductoresAnonimos Alter

indra/newview/CMakeLists.txt

@@ -1944,10 +1944,6 @@ elseif (DARWIN)
     set_target_properties(${VIEWER_BINARY_NAME}
         PROPERTIES
         LINK_FLAGS_RELEASE "${LINK_FLAGS_RELEASE} -Xlinker -dead_strip -Xlinker -map -Xlinker ${CMAKE_CURRENT_BINARY_DIR}/${VIEWER_BINARY_NAME}.MAP"
-        # Force the SDK version in the linked executable to be 10.12. This will fool
-        # macOS into using the pre-Mojave display system, avoiding the blurry display that
-        # otherwise occurs when upscaling the viewer to Retina resolution levels.
-        LINK_FLAGS_RELEASE "${LINK_FLAGS_RELEASE} -Xlinker -platform_version -Xlinker macos -Xlinker ${CMAKE_OSX_DEPLOYMENT_TARGET} -Xlinker 10.12"
         )
 else (WINDOWS)
         # Linux

indra/newview/Info-SecondLife.plist

@@ -79,7 +79,5 @@
 	<string>${MACOSX_BUNDLE_NSPRINCIPAL_CLASS}</string>
 	<key>NSMainNibFile</key>
 	<string>${MACOSX_BUNDLE_NSMAIN_NIB_FILE}</string>
-	<key>NSHighResolutionCapable</key>
-	<true/>
 </dict>
 </plist>