Fix -fno-common by moving fsck_data, from Gentoo
https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-fs/hfsplusutils/files/hfsplusutils-1.0.4-fno-common-gcc10.patch

Index: libhfsp/src/fscheck.h
--- libhfsp/src/fscheck.h.orig
+++ libhfsp/src/fscheck.h
@@ -100,10 +100,11 @@ int fscheck_btree(btree *bt);
 int fscheck_files(volume* vol);
 
 /** global data used during fsck */
-struct {
+struct fsck_data_t {
     UInt32  maxCnid;
     UInt32  macNow; // current date in mac-offset
     int	    verbose;
     int	    ignoreErr;
-} fsck_data;
+};
 
+extern struct fsck_data_t fsck_data;