Tex: don't try to be too smart regarding the .aux file

The previous version sometimes failed to rebuild a document after a
failed build attempt followed by a correct fix.

docs/tex_common/makefile.mk

@@ -20,10 +20,6 @@ fast:
 	@$(TEX) $(TEX_MAIN).tex
 	@"$(VIEW)" "$(CWD)/$(TEX_OUT)"
 
-$(TEX_MAIN).aux:
-	@$(TEX) $(TEX_MAIN).tex
-	@rm -f "$(CWD)/$(TEX_OUT)"
-
 view: $(TEX_OUT)
 	@"$(VIEW)" "$(CWD)/$(TEX_OUT)"
 	
@@ -31,9 +27,12 @@ clean:
 	@rm -f $(TEX_OUT) $(OUTDIR)*.aux $(OUTDIR)*.bcf $(OUTDIR)*.bbl $(OUTDIR)*-blx.bib $(OUTDIR)*.run.xml $(OUTDIR)*.idx $(OUTDIR)*.ilg $(OUTDIR)*.lot $(OUTDIR)*.lof $(OUTDIR)*.lol $(OUTDIR)*.blg $(OUTDIR)*.alg $(OUTDIR)*.ind $(OUTDIR)*.toc $(OUTDIR)*.acl $(OUTDIR)*.acn $(OUTDIR)*.acr $(OUTDIR)*.out $(OUTDIR)*.log $(OUTDIR)*.gls $(OUTDIR)*.glo $(OUTDIR)*.glg $(OUTDIR)*.ist $(OUTDIR)*.brf $(OUTDIR)*.ver $(OUTDIR)*.hst $(OUTDIR)*.glsdefs
 
 PREREQS := $(wildcard *.tex *.bib content/*.tex img/*.tex img/*.pdf img/*.png ../tex_common/*.tex ../tex_common/img/*.tex)
+
 $(JOB).pdf: $(TEX_MAIN).aux $(PREREQS)
+	@rm -f "$(CWD)/$(TEX_OUT)"
 # only run bibtex if there exist bib files
 ifneq (,$(filter %.bib,$(PREREQS)))
+	@$(TEX) $(TEX_MAIN).tex
 	$(BIB) $(OUTDIR)$(JOB)
 endif
 	#$(IDX) $(OUTDIR)$(JOB).idx