Try to fix FreeBSD detection with configure.

configure

@@ -4210,7 +4210,7 @@ fi
 # Detect OS
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether OS is FreeBSD" >&5
 $as_echo_n "checking whether OS is FreeBSD... " >&6; }
-if test "x$host_os" = "x*freebsd*"; then :
+if test "x$host_os" = "x*FreeBSD*"; then :
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
       LIBS="-lexecinfo $LIBS"

configure.ac

@@ -50,7 +50,7 @@ AC_ARG_ENABLE(qt-dbus,
 
 # Detect OS
 AC_MSG_CHECKING([whether OS is FreeBSD])
-AS_IF([test "x$host_os" = "x*freebsd*"],
+AS_IF([test "x$host_os" = "x*FreeBSD*"],
       [AC_MSG_RESULT([yes])
       LIBS="-lexecinfo $LIBS"],
       [AC_MSG_RESULT([no])])