Replace the --defsym linker argument with an alias in code

- This has the same effect as the  -defsym=__CFConstantStringClassReference=_T010Foundation19_NSCFConstantStringCN
  option but does it in code which allows simplifying the linker arguments.

Author: spevans

CoreFoundation/Base.subproj/CFInternal.h

@@ -349,7 +349,7 @@ CF_EXPORT void * __CFConstantStringClassReferencePtr;
 
 #if DEPLOYMENT_RUNTIME_SWIFT
 
-CF_EXPORT void *__CFConstantStringClassReference[];
+CF_EXPORT void *__CFConstantStringClassReference[] asm("_T010Foundation19_NSCFConstantStringCN");
 
 #if __CF_BIG_ENDIAN__
 #define CF_CONST_STRING_INFO {0x00, 0x00, 0x07, 0xc8}

build.py

@@ -16,7 +16,7 @@
 swift_cflags = ['-DDEPLOYMENT_RUNTIME_SWIFT']
 if Configuration.current.target.sdk == OSType.Linux:
 	foundation.CFLAGS = '-DDEPLOYMENT_TARGET_LINUX -D_GNU_SOURCE -DCF_CHARACTERSET_DATA_DIR="CoreFoundation/CharacterSets"'
-	foundation.LDFLAGS = '${SWIFT_USE_LINKER} -Wl,@./CoreFoundation/linux.ld -lswiftGlibc `${PKG_CONFIG} icu-uc icu-i18n --libs` -Wl,-defsym,__CFConstantStringClassReference=_T010Foundation19_NSCFConstantStringCN -Wl,-Bsymbolic '
+	foundation.LDFLAGS = '${SWIFT_USE_LINKER} -Wl,@./CoreFoundation/linux.ld -lswiftGlibc `${PKG_CONFIG} icu-uc icu-i18n --libs` -Wl,-Bsymbolic '
 	Configuration.current.requires_pkg_config = True
 elif Configuration.current.target.sdk == OSType.FreeBSD:
 	foundation.CFLAGS = '-DDEPLOYMENT_TARGET_FREEBSD -I/usr/local/include -I/usr/local/include/libxml2 -I/usr/local/include/curl '
@@ -26,7 +26,7 @@
 	foundation.LDFLAGS = '-licucore -twolevel_namespace -Wl,-alias_list,CoreFoundation/Base.subproj/DarwinSymbolAliases -sectcreate __UNICODE __csbitmaps CoreFoundation/CharacterSets/CFCharacterSetBitmaps.bitmap -sectcreate __UNICODE __properties CoreFoundation/CharacterSets/CFUniCharPropertyDatabase.data -sectcreate __UNICODE __data CoreFoundation/CharacterSets/CFUnicodeData-L.mapping -segprot __UNICODE r r '
 elif Configuration.current.target.sdk == OSType.Win32 and Configuration.current.target.environ == EnvironmentType.Cygnus:
 	foundation.CFLAGS = '-DDEPLOYMENT_TARGET_LINUX -D_GNU_SOURCE -mcmodel=large '
-	foundation.LDFLAGS = '${SWIFT_USE_LINKER} -lswiftGlibc `icu-config --ldflags` -Wl,-defsym,__CFConstantStringClassReference=_T010Foundation19_NSCFConstantStringCN,--allow-multiple-definition '
+	foundation.LDFLAGS = '${SWIFT_USE_LINKER} -lswiftGlibc `icu-config --ldflags` -Wl,--allow-multiple-definition '
 	swift_cflags += ['-DCYGWIN']
 
 if Configuration.current.build_mode == Configuration.Debug: