Get rid of the YACCFLAGS build variable

It was not used, except in lex/Makefile where this commit replaces its
unique occurrence by its definition in the same file.

Makefile

@@ -53,7 +53,6 @@ else
 OCAML_NATDYNLINKOPTS = -ccopt "$(NATDYNLINKOPTS)"
 endif
 
-YACCFLAGS=-v --strict
 CAMLLEX=$(CAMLRUN) boot/ocamllex
 CAMLDEP=$(CAMLRUN) boot/ocamlc -depend
 DEPFLAGS=-slash

debugger/Makefile

@@ -27,7 +27,6 @@ CAMLC=$(BEST_OCAMLC) -g -nostdlib -I $(ROOTDIR)/stdlib
 COMPFLAGS=$(INCLUDES) -absname -w +a-4-9-41-42-44-45-48 -warn-error A \
           -safe-string -strict-sequence -strict-formats
 LINKFLAGS=-linkall -I $(UNIXDIR) -I $(DYNLINKDIR)
-YACCFLAGS=
 CAMLLEX=$(BEST_OCAMLLEX)
 CAMLDEP=$(BEST_OCAMLDEP)
 DEPFLAGS=-slash

lex/Makefile

@@ -27,7 +27,6 @@ CAMLOPT = $(CAMLRUN) $(ROOTDIR)/ocamlopt$(EXE) -nostdlib -I $(ROOTDIR)/stdlib
 COMPFLAGS = -absname -w +a-4-9-41-42-44-45-48 -warn-error A \
             -safe-string -strict-sequence -strict-formats -bin-annot
 LINKFLAGS =
-YACCFLAGS = -v
 CAMLLEX = $(CAMLRUN) $(ROOTDIR)/boot/ocamllex
 CAMLDEP = $(BOOT_OCAMLC) -depend
 DEPFLAGS = -slash
@@ -56,7 +55,7 @@ clean::
 	rm -f *.cmo *.cmi *.cmx *.cmt *.cmti *.o *.obj
 
 parser.ml parser.mli: parser.mly
-	$(CAMLYACC) $(YACCFLAGS) parser.mly
+	$(CAMLYACC) -v parser.mly
 
 clean::
 	rm -f parser.ml parser.mli parser.output