Fix signature parsing on 32-bit big-endian
Fix signature parsing on 32-bit big-endian

(Fixes test-pe on Debian/powerpc and Debian/hppa.)

wxsBSD/yara,wxsBSD/yara,pombredanne/yara,cblichmann/yara,wxsBSD/yara,cblichmann/yara,pombredanne/yara,wxsBSD/yara,cblichmann/yara,hillu/yara,pombredanne/yara,pombredanne/yara,VirusTotal/yara,hillu/yara,hillu/yara,wxsBSD/yara,pombredanne/yara,VirusTotal/yara,hillu/yara,VirusTotal/yara,hillu/yara,cblichmann/yara,cblichmann/yara,VirusTotal/yara,VirusTotal/yara