autoconf: More informative errors when pkg-config macros undefined

Added a check that PKG_PROG_PKG_CONFIG is defined before calling it so
the user can see a proper error. Without it, the generated configure
script will just pass on to the next statement and bomb with a strange
shell syntax error.

diff --git a/configure.ac b/configure.ac
index 4cd641b136be4ff40cfa2fae5c89fa9f56e32f9e..40c39b9912209b7a6f52cfec5aa646514b9228d8 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -28,6 +28,12 @@ AC_PROG_CXX
 AC_PATH_PROG(MAKE, make)
 AC_PATH_PROG(MKDEP, makedepend)
 AC_PATH_PROG(SED, sed)
+
+dnl Make sure the pkg-config macros are defined
+m4_ifdef([PKG_PROG_PKG_CONFIG],,[
+    AC_MSG_ERROR([The pkg-config autoconf macros are not defined.
+                  Did you run 'make configure'?])]
+)
 PKG_PROG_PKG_CONFIG()
 
 dnl LIB_DIR - library basename