Problem: autoconf does not use pkgconfig for NORM

Solution: use the pkgconfig macro as the first step and then fallback
to manual checks

Makefile.am

@@ -307,6 +307,11 @@ src_libzmq_la_CPPFLAGS += ${pgm_CFLAGS}
 src_libzmq_la_LIBADD += ${pgm_LIBS}
 endif
 
+if HAVE_NORM
+src_libzmq_la_CPPFLAGS += ${norm_CFLAGS}
+src_libzmq_la_LIBADD += ${norm_LIBS}
+endif
+
 if BUILD_GSSAPI
 src_libzmq_la_CPPFLAGS += ${gssapi_krb5_CFLAGS}
 src_libzmq_la_LIBADD += ${gssapi_krb5_LIBS}

configure.ac

@@ -537,19 +537,29 @@ AC_ARG_WITH([norm],
 AC_MSG_CHECKING("with_norm_ext = ${with_norm_ext}")
 
 if test "x$with_norm_ext" != "xno"; then
+    PKG_CHECK_MODULES([norm], [norm], [ have_norm_library="yes" ], [
         AC_MSG_RESULT([yes])
-    AC_DEFINE(ZMQ_HAVE_NORM, 1, [Have NORM protocol extension])
 
+        norm_LIBS=""
+        norm_CFLAGS=""
         if test "x$with_norm_ext" != "xyes"; then
             norm_path="${with_norm_ext}"
-        LIBZMQ_EXTRA_CXXFLAGS="-I${norm_path}/include ${LIBZMQ_EXTRA_CXXFLAGS}"
-        LIBZMQ_EXTRA_LDFLAGS="-L${norm_path}/lib ${LIBZMQ_EXTRA_LDFLAGS}"
+            norm_CFLAGS="${norm_CFLAGS} -I${norm_path}/include"
+            norm_LIBS="${norm_LIBS} -L${norm_path}/lib"
         fi
-    LIBS="-L${norm_path}/lib -lnorm $LIBS"
-    PKGCFG_LIBS_PRIVATE="$PKGCFG_LIBS_PRIVATE -lnorm"
+        norm_LIBS="${norm_LIBS} -lnorm"
+        have_norm_library="yes"
+        AC_SUBST(norm_LIBS)
+        AC_SUBST(norm_CFLAGS)
+    ])
 else
     AC_MSG_RESULT([no])
 fi
+if test "x$have_norm_library" = "xyes"; then
+    AC_DEFINE(ZMQ_HAVE_NORM, [1], [Have NORM protocol extension])
+    PKGCFG_LIBS_PRIVATE="$PKGCFG_LIBS_PRIVATE $norm_LIBS"
+fi
+AM_CONDITIONAL(HAVE_NORM, test "x$have_norm_library" = "xyes")
 
 # build using vmci
 have_vmci_library="no"