WIP: Elf64 shlib compress+decompress seems to work

modified:   p_lx_elf.cpp
	modified:   p_lx_elf.h
	modified:   p_unix.cpp

src/p_lx_elf.h

@@ -92,6 +92,7 @@ protected:
     upx_uint64_t user_init_va;
     unsigned user_init_off;  // within file_image
     unsigned linfo_off;
+    unsigned loader_offset;  // during de-compression
 
     upx_uint16_t  e_machine;
     unsigned char ei_class;