make option for specific files

[lisa-asket]

Have the following makefile and want to have an easy way to build "*rfc.texi" 
files using

"make rfc".



.PHONY: all new again clean

ch6 := $(wildcard *amcoh.texi)
igm := $(wildcard *igm.texi)
rfc := $(wildcard *rfc.texi)

pdfs := $(tfiles:.texi=.pdf)

all: ${pdfs}

%.pdf: %.texi
    texi2pdf $< -o $@

clean:
    rm -f ${pdfs}

again:
    ${MAKE} clean
    ${MAKE}

new:
    ${MAKE} again