Add experimental manifest.scm for testing Autoconf under guix shell.

‘guix shell’ is a utility for constructing isolated environments
for development; I’ve put together a “manifest” stating the
build and test requirements for autoconf, starting from a git
checkout.

manifest.scm

@@ -0,0 +1,51 @@
+;; Guix manifest for testing Autoconf in an isolated environment.
+;; Use as e.g.
+;;   guix shell --container --manifest=manifest.scm
+;; Everything required for the release checks (see HACKING) is included.
+
+;; Copying and distribution of this file, with or without modification,
+;; are permitted in any medium without royalty provided the copyright
+;; notice and this notice are preserved.  This file is offered as-is,
+;; without any warranty.
+
+(specifications->manifest
+ '(
+   ;; Basic requirements for a standard "gnu build system" build.
+   ;; TODO: Make a variant with a stripped-down environment,
+   ;; perhaps using busybox or toybox instead of coreutils and friends.
+   ;; TODO: Investigate why the syntax error tests fail with bash-minimal.
+   "bash" "coreutils" "diffutils" "findutils" "gawk" "grep" "make" "sed"
+   "tar" "gzip" "xz" ; bzip2 intentionally left out
+
+   ;; Additional requirements for building and running Autoconf itself.
+   "m4" "perl"
+
+   ;; Additional requirements for building from a pristine git checkout.
+   "automake" "git" "help2man" "texinfo"
+   "texlive"  ; shouldn't be necessary - standards.texi requires ectt which
+              ; doesn't seem to be in any smaller package
+
+   ;; All of the compilers and tools that Autoconf is capable of probing.
+   ;;
+   ;; TODO: Make a variant that *doesn't* install any of this
+   ;; and ensure that every test that requires at least one compiler is
+   ;; skipped, rather than failing, when run in that environment.  Currently
+   ;; lots of tests fail in the absence of a C compiler.
+   ;;
+   ;; TODO: Investigate why "gcc-toolchain" produces a working compiler,
+   ;; and "ld-wrapper" "binutils" "gcc" doesn't, when the former is
+   ;; supposedly just a dependency package that pulls in the latter three.
+   ;; (It probably has something to do with how "gcc-toolchain" also pulls
+   ;; half a dozen "boot" packages that shouldn't be necessary at all,
+   ;; even though these are not listed in its dependencies.)
+   "gcc-toolchain"  ; C, C++, infrastructure
+   "gcc-objc"       ; Objective-C
+   "gccgo"          ; Go
+   ;"gfortran"      ; Fortran - not currently available??
+   "erlang"         ; Erlang
+
+   "bison"
+   "flex"
+   "libtool"
+   ;"shtool"        ; not currently available
+))