Xcode: apply suggested changes from Xcode 11.2

Enable code signing.
diff --git a/Xcode/libusb.xcodeproj/project.pbxproj b/Xcode/libusb.xcodeproj/project.pbxproj
index 9b5c125..577a13c 100644
--- a/Xcode/libusb.xcodeproj/project.pbxproj
+++ b/Xcode/libusb.xcodeproj/project.pbxproj
@@ -567,7 +567,7 @@
 		008FBF281628B79300BC5BE2 /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1030;
+				LastUpgradeCheck = 1120;
 				ORGANIZATIONNAME = libusb;
 				TargetAttributes = {
 					006AD41B1C8C5A90007F8C6A = {
@@ -738,6 +738,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -747,6 +748,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
@@ -808,6 +810,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -817,6 +820,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
@@ -826,6 +830,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -835,6 +840,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
@@ -844,6 +850,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -853,6 +860,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
@@ -862,6 +870,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -871,6 +880,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
@@ -880,6 +890,7 @@
 			baseConfigurationReference = 1443EE8516417E63007E0579 /* debug.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Debug;
@@ -889,6 +900,7 @@
 			baseConfigurationReference = 1443EE8816417E63007E0579 /* release.xcconfig */;
 			buildSettings = {
 				CLANG_ENABLE_OBJC_WEAK = YES;
+				CODE_SIGN_IDENTITY = "-";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 			};
 			name = Release;
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index dcea538..3681e1d 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11408
+#define LIBUSB_NANO 11409