macOS: Fix love.framework's runpath search path

Fixes loading love.framework from a standalone Lua executable, and potentially fixes some code signing issues (#1737)

platform/xcode/liblove.xcodeproj/project.pbxproj

@@ -4951,7 +4951,6 @@
 					"\"$(SRCROOT)/../../src/libraries/enet/libenet/include\"",
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
-				LD_RUNPATH_SEARCH_PATHS = "@rpath";
 				LIBRARY_SEARCH_PATHS = "";
 				MACOSX_DEPLOYMENT_TARGET = 10.7;
 				ONLY_ACTIVE_ARCH = NO;
@@ -5017,7 +5016,6 @@
 					"\"$(SRCROOT)/../../src/libraries/enet/libenet/include\"",
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
-				LD_RUNPATH_SEARCH_PATHS = "@rpath";
 				LIBRARY_SEARCH_PATHS = "";
 				MACOSX_DEPLOYMENT_TARGET = 10.7;
 				ONLY_ACTIVE_ARCH = YES;
@@ -5158,7 +5156,6 @@
 					"\"$(SRCROOT)/../../src/libraries/enet/libenet/include\"",
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
-				LD_RUNPATH_SEARCH_PATHS = "@rpath";
 				LIBRARY_SEARCH_PATHS = "";
 				LLVM_LTO = YES;
 				MACOSX_DEPLOYMENT_TARGET = 10.7;
@@ -5193,6 +5190,7 @@
 				);
 				INFOPLIST_FILE = "macosx/liblove-macosx.plist";
 				LD_DYLIB_INSTALL_NAME = "@rpath/$(EXECUTABLE_PATH)";
+				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../../../";
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/ios/libraries/freetype",
@@ -5232,6 +5230,7 @@
 				);
 				INFOPLIST_FILE = "macosx/liblove-macosx.plist";
 				LD_DYLIB_INSTALL_NAME = "@rpath/$(EXECUTABLE_PATH)";
+				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../../../";
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/ios/libraries/freetype",
@@ -5272,6 +5271,7 @@
 				);
 				INFOPLIST_FILE = "macosx/liblove-macosx.plist";
 				LD_DYLIB_INSTALL_NAME = "@rpath/$(EXECUTABLE_PATH)";
+				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../../../";
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)/ios/libraries/freetype",