Use pkg-config macro to check for libgpiod

This also restricts supported version of libgpiod to < 2.0.0.

Author: havardAasen

src/configure.ac

@@ -533,11 +533,12 @@ install with "sudo apt-get install libusb-1.0-0-dev" or disable with
 #
 # check for libgpiod
 #
-AC_MSG_CHECKING([for libgpiod])
-AC_CHECK_LIB(gpiod, main,
+PKG_CHECK_MODULES([LIBGPIOD], [libgpiod < 2.0.0],
             [AC_DEFINE_UNQUOTED([LIBGPIOD_VER], `pkg-config libgpiod --modversion | awk -F. '{print ($1 * 100)+($2) }'`,
             [libgpiod version, undefined if not present])
-            LDFLAGS="$LDFLAGS -lgpiod"
+            LDFLAGS="$LDFLAGS $LIBGPIOD_LIBS"
+            LIBGPIOD_VERSION=`pkg-config libgpiod --modversion`
+            AC_MSG_NOTICE([libgpiod version $LIBGPIOD_VERSION found])
             AC_SUBST([LIBGPIOD_VER], `pkg-config libgpiod --modversion | awk -F. '{print ($1 * 100)+($2) }'`)],
             [AC_MSG_WARN([Could not find libgpiod, not building hal_gpio])])