commit 755677baae16fd8772efd523a25b787ea3fc0772
Author: hasufell <hasufell@gentoo.org>
Date:   Sat Jul 13 13:26:24 2013 +0200

    BUILD: add --with-gps switch
    
    We don't want automagic gps detection, but give control
    to the user.

diff --git a/configure.ac b/configure.ac
index 86c7569..307def4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -156,6 +156,12 @@ if test -z "${SKIP_COMPLICATED}"; then
 fi
 CXXFLAGS="${SAVED_CXXFLAGS}"
 
+AC_ARG_WITH([gps],
+            [AS_HELP_STRING([--with-gps],
+              [use libgpsd (default: no)])],
+            [gps=$withval],
+            [gps=no])
+
 # xttpd configs
 AC_ARG_WITH([xttpd-user],
             [AS_HELP_STRING([--with-xttpd-user=user],
@@ -381,32 +387,35 @@ AC_CHECK_HEADER([Dstr], [AC_CHECK_LIB([dstr], [DstrCompat20070215Check])])
 AM_CONDITIONAL(NO_LIBDSTR, test "$ac_cv_lib_dstr_DstrCompat20070215Check" != "yes")
 
 # libgps is optional; use it if you have a compatible version.
-AC_CHECK_HEADER([gps.h], [AC_CHECK_LIB([gps], [timestamp], [
-  AC_MSG_CHECKING([if libgps is 3.x or newer, compatible version])
-  AC_COMPILE_IFELSE(
-    [AC_LANG_SOURCE([[
-#include <gps.h>
-#if (GPSD_API_MAJOR_VERSION < 5)
-#FAIL
-#endif
-int main (int argc, char **argv) {
-  struct gps_data_t gpsdata;
-  gps_open ("127.0.0.1", "2947", &gpsdata);
-  gps_stream (&gpsdata, WATCH_ENABLE|WATCH_NEWSTYLE, NULL);
-  gps_read (&gpsdata);
-  return (gpsdata.fix.mode >= MODE_2D);
-}
-    ]])],
-    [
-      AC_MSG_RESULT(yes)
-      AC_DEFINE([GPS_GOOD])
-      AC_SUBST([GPSD_LIBS], ["-lgps"])
-    ],
-    [
-      AC_MSG_RESULT(no)
-    ]
-  )
-])])
+
+AS_IF([test "x$gps" = "xyes"], [
+	AC_CHECK_HEADER([gps.h], [AC_CHECK_LIB([gps], [timestamp], [
+	  AC_MSG_CHECKING([if libgps is 3.x or newer, compatible version])
+	  AC_COMPILE_IFELSE(
+		[AC_LANG_SOURCE([[
+	#include <gps.h>
+	#if (GPSD_API_MAJOR_VERSION < 5)
+	#FAIL
+	#endif
+	int main (int argc, char **argv) {
+	  struct gps_data_t gpsdata;
+	  gps_open ("127.0.0.1", "2947", &gpsdata);
+	  gps_stream (&gpsdata, WATCH_ENABLE|WATCH_NEWSTYLE, NULL);
+	  gps_read (&gpsdata);
+	  return (gpsdata.fix.mode >= MODE_2D);
+	}
+		]])],
+		[
+		  AC_MSG_RESULT(yes)
+		  AC_DEFINE([GPS_GOOD])
+		  AC_SUBST([GPSD_LIBS], ["-lgps"])
+		],
+		[
+		  AC_MSG_RESULT(no)
+		]
+	  )
+	], [AC_MSG_ERROR([cannot find libgps])])], [AC_MSG_ERROR([cannot find gps.h])])
+	])
 
 AC_TYPE_INT8_T
 AC_TYPE_INT16_T