confusing message in AC_PROG_MAKE_SET

[Bruno Haible]

Hi,

autoconf-2.54b generated configure file prints for AC_PROG_MAKE_SET

checking whether make sets ${MAKE}

This is confusing because in common use ${X} means a shell variable, whereas
$(X) means a makefile variable. Yes I know ${X} is synonymous to $(X) in
Makefiles, but nevertheless the common notation in Makefiles is $(X). So the
message should better read

checking whether make sets $(MAKE)

Btw, here is a test makefile that tests for MAKE being set as a shell
variable, and this tests fails with GNU make.

all:
        @eval echo 'ac_maketemp="$$''{MAKE}"'