[Build] Update MACOSX_DEPLOYMENT_TARGET to macOS 11

And enable the compiler options equivalent to the Xcode options
- CLANG_WARN_UNGUARDED_AVAILABILITY = yes
- GCC_TREAT_WARNINGS_AS_ERRORS = yes

Author: HannesWell

bundles/org.eclipse.swt/Eclipse SWT PI/cocoa/library/build.sh

@@ -29,6 +29,6 @@ elif [ "x${MODEL}" = "xarm64" ] || [ "x${MODEL}" = "xaarch64" ]; then
 	fi
 fi
 
-export MACOSX_DEPLOYMENT_TARGET=10.10
+export MACOSX_DEPLOYMENT_TARGET=11
 
 make -f make_macosx.mak $1 $2 $3 $4 $5 $6 $7 $8 $9

bundles/org.eclipse.swt/Eclipse SWT PI/cocoa/library/make_macosx.mak

@@ -34,6 +34,7 @@ AWT_OBJECTS   = swt_awt.o
 
 #SWT_DEBUG = -g
 CFLAGS = -c -xobjective-c -Wall $(ARCHS) $(SWT_DEBUG) -DUSE_ASSEMBLER -DCOCOA -DATOMIC \
+	-Wunguarded-availability -Werror\
 	-I $(SWT_JAVA_HOME)/include \
 	-I $(SWT_JAVA_HOME)/include/darwin \
 	-I /System/Library/Frameworks/Cocoa.framework/Headers \