build: Require Guile >= 2.0.7.

* configure.ac: Require guile-2.0 >= 2.0.7.
* README: Adjust accordingly.
* doc/guix.texi (Requirements): Likewise.

README

@@ -20,7 +20,7 @@ Guix is based on the [[http://nixos.org/nix/][Nix]] package manager.
 
 GNU Guix currently depends on the following packages:
 
-  - [[http://gnu.org/software/guile/][GNU Guile 2.0.x]], version 2.0.5 or later
+  - [[http://gnu.org/software/guile/][GNU Guile 2.0.x]], version 2.0.7 or later
   - [[http://gnupg.org/][GNU libgcrypt]]
   - optionally [[http://savannah.nongnu.org/projects/guile-json/][Guile-JSON]], for the 'guix import pypi' command
   - optionally [[http://www.gnutls.org][GnuTLS]] compiled with guile support enabled, for HTTPS support

configure.ac

@@ -67,7 +67,7 @@ dnl Make sure they are available.
 m4_pattern_forbid([PKG_CHECK_MODULES])
 m4_pattern_forbid([GUILE_MODULE_AVAILABLE])
 
-PKG_CHECK_MODULES([GUILE], [guile-2.0 >= 2.0.5])
+PKG_CHECK_MODULES([GUILE], [guile-2.0 >= 2.0.7])
 AC_PATH_PROG([GUILE], [guile])
 AC_PATH_PROG([GUILD], [guild])
 if test "x$GUILD" = "x"; then

doc/guix.texi

@@ -332,7 +332,7 @@ in the Guix source tree for additional details.
 GNU Guix depends on the following packages:
 
 @itemize
-@item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.5 or later;
+@item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
 @item @url{http://gnupg.org/, GNU libgcrypt};
 @end itemize