languages.yml: support GNUmakefile and makefile
languages.yml: support GNUmakefile and makefile

GNU make manpage says: "If  no  -f  option  is present,  make will look
for the makefiles GNUmakefile, makefile, and Makefile, in that order."
mattn/linguist,sebgod/linguist,erkyrath/linguist,yyx990803/linguist,R4PaSs/linguist,mcandre/linguist,iblech/linguist,sebgod/linguist,FStarLang/linguist,nburkley/linguist,stanhu/linguist,chiranjeevjain/linguist,github/linguist,seanders/linguist,thejameskyle/linguist,anhongyue/test222,BerkeleyTrue/linguist,pchaigno/linguist,hcatlin/linguist,mcandre/linguist,leafo/linguist,alitalia/linguist,CegepVictoriaville/linguist,alitalia/linguist,martynbm/linguist,yscho/linguist,georgesuperman/linguist,davidzchen/linguist,georgesuperman/linguist,sebgod/linguist,BerkeleyTrue/linguist,igrigorik/linguist,FStarLang/linguist,yyx990803/linguist,phpsgi/linguist,adamkaplan/linguist,jrnold/linguist,sagar290/linguist,yyx990803/linguist,Mailaender/linguist,alvarotrigo/linguist,MadcapJake/linguist,sideci-sample/sideci-sample-linguist,ChaiScript/linguist,Ocramius/linguist,erkyrath/linguist,ammaraskar/linguist,pcantrell/linguist,mwpastore/linguist,jrnold/linguist,assimovt/ling-ist,SRI-CSL/linguist,JJ/linguist,R4PaSs/linguist,pchaigno/linguist,ya7lelkom/linguist,wcandillon/linguist,cybernet14/linguist,adamkaplan/linguist,tschf/linguist,tschf/linguist,osorgin/linguist,maxogden/linguist,a0viedo/linguist,davidzchen/linguist,c-lipka/linguist,ppaulweber/github-linguist,JJ/linguist,whitj00/linguist,kr/linguist,a0viedo/linguist,hcutler/linguist,matt40k/linguist,mattn/linguist,meunierfrederic/octocatlinguist,marcojonker/test,Mx7f/linguist,cokeboL/linguist,meunierfrederic/octocatlinguist,stanhu/linguist,0a-/linguist,pcantrell/linguist,nburkley/linguist,phpsgi/linguist,scttnlsn/linguist,JJ/linguist,osorgin/linguist,0a-/linguist,stanhu/linguist,CoderXpert/linguist,jtbandes/linguist,erkyrath/linguist,blakeembrey/linguist,kr/linguist,cybernet14/linguist,seanders/linguist,CoderXpert/linguist,cokeboL/linguist,PsichiX/linguist,marcojonker/test,MahmoudFayed/linguist,MostAwesomeDude/linguist,iblech/linguist,thejameskyle/linguist,MadcapJake/linguist,matt40k/linguist,github/linguist,assimovt/ling-ist,gitlabhq/linguist,jtbandes/linguist,github/linguist,hcutler/linguist,github/linguist,blakeembrey/linguist,douglas-larocca/linguist,ilyes14/linguist,PsichiX/linguist,erkyrath/linguist,MostAwesomeDude/linguist,yscho/linguist,MahmoudFayed/linguist,martynbm/linguist,igat259/linguist,pchaigno/linguist,bluebear94/linguist,alvarotrigo/linguist,ammaraskar/linguist,c-lipka/linguist,SRI-CSL/linguist,manveru/linguist,Mx7f/linguist,ppaulweber/github-linguist,Rockyspade/linguist,ilyes14/linguist,wcandillon/linguist,manveru/linguist,christop/linguist,kyoungrok0517/linguist,ya7lelkom/linguist,CegepVictoriaville/linguist,whitj00/linguist,kyoungrok0517/linguist,bluebear94/linguist,sagar290/linguist,hcatlin/linguist,steventhanna/linguist,sebgod/linguist,mwpastore/linguist,jjatria/linguist,sideci-sample/sideci-sample-linguist,steventhanna/linguist,douglas-larocca/linguist,christop/linguist,jjatria/linguist,stanhu/linguist,chiranjeevjain/linguist,pchaigno/linguist,JJ/linguist,scttnlsn/linguist,meunierfrederic/octocatlinguist,Rockyspade/linguist,yyx990803/linguist,anhongyue/test222