Xcode project: add FIFODIR to preprocessor macros

… in order to avoid a compiler warning.

projectfiles/Xcode/Wesnoth.xcodeproj/project.pbxproj

@@ -4862,6 +4862,10 @@
 				GCC_ENABLE_FIX_AND_CONTINUE = NO;
 				GCC_MODEL_TUNING = G5;
 				GCC_OPTIMIZATION_LEVEL = 0;
+				GCC_PREPROCESSOR_DEFINITIONS = (
+					"LOCALEDIR=\\\"translations\\\"",
+					"FIFODIR=\\\"/var/run/wesnothd\\\"",
+				);
 				GCC_VERSION = com.apple.compilers.llvm.clang.1_0;
 				INSTALL_PATH = /usr/local/bin;
 				LIBRARY_SEARCH_PATHS = (
@@ -4883,6 +4887,10 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				COPY_PHASE_STRIP = YES;
+				GCC_PREPROCESSOR_DEFINITIONS = (
+					"LOCALEDIR=\\\"translations\\\"",
+					"FIFODIR=\\\"/var/run/wesnothd\\\"",
+				);
 				INSTALL_PATH = /usr/local/bin;
 				LIBRARY_SEARCH_PATHS = (
 					"$(inherited)",