krb5: don't include plist support unless CoreFoundation is present

depending what's available when you compile for iOS it's possible to
be __APPLE__ and not have CF; actually test for it instead of blythely
assuming it can be used

lib/krb5/Makefile.am

@@ -253,6 +253,9 @@ libkrb5_la_DEPENDENCIES =			\
 	version-script.map
 
 libkrb5_la_LDFLAGS = -version-info 26:0:0
+if FRAMEWORK_COREFOUNDATION
+libkrb5_la_LDFLAGS += -framework CoreFoundation
+endif
 
 if versionscript
 libkrb5_la_LDFLAGS += $(LDFLAGS_VERSION_SCRIPT)$(srcdir)/version-script.map

lib/krb5/config_file.c

@@ -35,7 +35,7 @@
 
 #include "krb5_locl.h"
 
-#ifdef __APPLE__
+#if defined(HAVE_FRAMEWORK_COREFOUNDATION)
 #include <CoreFoundation/CoreFoundation.h>
 #endif
 
@@ -238,7 +238,7 @@ parse_binding(struct fileptr *f, unsigned *lineno, char *p,
     return ret;
 }
 
-#if defined(__APPLE__)
+#if defined(HAVE_FRAMEWORK_COREFOUNDATION)
 
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= 1060
 #define HAVE_CFPROPERTYLISTCREATEWITHSTREAM 1
@@ -605,7 +605,7 @@ krb5_config_parse_file_multi (krb5_context context,
 
     if (is_plist_file(fname)) {
         context->config_include_depth--;
-#ifdef __APPLE__
+#if defined(HAVE_FRAMEWORK_COREFOUNDATION)
 	ret = parse_plist_config(context, fname, res);
 	if (ret) {
 	    krb5_set_error_message(context, ret,