2016-04-19: Use GUILE_PKG instead of PKG_CHECK_MODULES

Use GUILE_PKG instead of PKG_CHECK_MODULES

diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,7 +9,7 @@ lang_DATA = language/wisp/spec.scm
 WISP = wisp-guile.w wisp-reader.w wisp-scheme.w
 
 EXTRA_DIST = $(WISP) bootstrap.sh bootstrap-reader.sh examples tests wisp-repl-guile.sh testrunner.w wisp.py wisp.scm
-DISTCLEANFILES = ${CLEANFILES} @abs_top_builddir@/1 @abs_top_builddir@/2 @abs_top_builddir@/syntaxtests.sh @abs_top_builddir@/syntaxtestsreader.sh
+CLEANFILES = 1 2
 # don't spout out lots of stuff at each distcheck. Disable for debugging.
 AM_DISTCHECK_CONFIGURE_FLAGS="--quiet"
 
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@ AC_CANONICAL_TARGET
 # search for Guile using the guile m4 files.
 # see https://www.gnu.org/software/guile/manual/html_node/Autoconf-Macros.html
 # This provides @GUILE@ to Makefile.am
-PKG_CHECK_MODULES(GUILE, guile-2.0 >= 2.0.11)
+GUILE_PKG([2.2 2.0 1.8])
 GUILE_PROGS
 GUILE_SITE_DIR