WavPack symbols need to be visible by default

They're not marked as exported, so we need to make all symbols visible for release Xcode builds

(cherry picked from commit f8fc299)

Author: slouken

Xcode/wavpack/wavpack.xcodeproj/project.pbxproj

@@ -367,7 +367,6 @@
 					"$(CONFIG_PREPROCESSOR_DEFINITIONS)",
 					ENABLE_DSD,
 				);
-				GCC_SYMBOLS_PRIVATE_EXTERN = YES;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
 				GCC_WARN_UNDECLARED_SELECTOR = YES;
@@ -441,7 +440,6 @@
 					"$(CONFIG_PREPROCESSOR_DEFINITIONS)",
 					ENABLE_DSD,
 				);
-				GCC_SYMBOLS_PRIVATE_EXTERN = YES;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
 				GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR;
 				GCC_WARN_UNDECLARED_SELECTOR = YES;