Fix bison warning.
Fix bison warning.

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