Preserve Mach_segment_header.flags; fix non-PIE main programs on MacOS.

https://github.com/upx/upx/issues/222
	modified:   p_mach.cpp
	modified:   p_mach.h
	modified:   stub/src/amd64-darwin.macho-entry.S
	also *.macho-*.h, *.macho-fold.map, amd64-darwin.macho-entry.bin.dump

src/p_mach.h

@@ -823,6 +823,7 @@ protected:
     unsigned o__mod_init_func;  // file offset to __DATA.__mod_init_func Mach_section_command
     upx_uint64_t prev_mod_init_func;
     upx_uint64_t pagezero_vmsize;
+    upx_uint64_t vma_max;  // max over (.vmsize + .vmaddr)
     Mach_header mhdri;
 
     Mach_header mhdro;