build: Rework how MULTIPATH_NUM is delivered to build

Changes made here:

1) MULTIPATH_NUM will never be 0.  If user specifies --enable-multipath=0
then this translates to MULTIPATH_NUM being set to 64 inside of the build
system.

2) Move MULTIPATH_NUM from a Makefile construct to a config.h construct.

3) Allowed MULTIPATH_NUM to be a number > 99 but < 1000

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/bgpd/Makefile.am b/bgpd/Makefile.am
index 7da4dd8..d2775f3 100644
--- a/bgpd/Makefile.am
+++ b/bgpd/Makefile.am
@@ -1,7 +1,7 @@
 ## Process this file with automake to produce Makefile.in.
 
 AM_CPPFLAGS = -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib
-DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\" -DMULTIPATH_NUM=@MULTIPATH_NUM@
+DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\"
 INSTALL_SDATA=@INSTALL@ -m 600
 
 AM_CFLAGS = $(WERROR)
diff --git a/configure.ac b/configure.ac
index b4d934b..7aaacb9 100755
--- a/configure.ac
+++ b/configure.ac
@@ -379,11 +379,14 @@
 enable_logfile_mask=${enable_logfile_mask:-0600}
 AC_DEFINE_UNQUOTED(LOGFILE_MASK, ${enable_logfile_mask}, Mask for log files)
 
-MULTIPATH_NUM=1
+MPATH_NUM=1
 
 case "${enable_multipath}" in
-  [[0-9]|[1-9][0-9]])
-    MULTIPATH_NUM="${enable_multipath}"
+  0)
+    MPATH_NUM=64
+    ;;
+  [[1-9]|[1-9][0-9]|[1-9][0-9][0-9]])
+    MPATH_NUM="${enable_multipath}"
     ;;
   "")
     ;;
@@ -392,7 +395,7 @@
     ;;
 esac
 
-AC_SUBST(MULTIPATH_NUM)
+AC_DEFINE_UNQUOTED(MULTIPATH_NUM, $MPATH_NUM, Maximum number of paths for a route)
 
 dnl -----------------------------------
 dnl Add extra version string to package
diff --git a/zebra/Makefile.am b/zebra/Makefile.am
index 96dc6f0..90ce7b9 100644
--- a/zebra/Makefile.am
+++ b/zebra/Makefile.am
@@ -1,7 +1,7 @@
 ## Process this file with automake to produce Makefile.in.
 
 AM_CPPFLAGS = -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib
-DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\" -DMULTIPATH_NUM=@MULTIPATH_NUM@
+DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\"
 INSTALL_SDATA=@INSTALL@ -m 600
 
 LIBCAP = @LIBCAP@