https://bugs.gentoo.org/770484
This is a stub definition, it broke linking and was unneeded
--- a/src/test/testsh4x86.c
+++ b/src/test/testsh4x86.c
@@ -113,7 +113,6 @@
 gboolean FASTCALL mmu_update_icache( sh4vma_t addr ) { return TRUE; }
 void MMU_ldtlb() { }
 struct sh4_icache_struct sh4_icache;
-struct mem_region_fn mem_region_unmapped;
 
 void usage()
 {