Online update: Enable online update even for the Linux release builds.

[and mention it explicitly in the Windows and Mac distro configs, to be
safe :-)]

distro-configs/LibreOfficeLinux.conf

@@ -41,6 +41,7 @@
 --enable-cairo
 --enable-binfilter
 --enable-python=internal
+--enable-online-update
 --disable-unix-qstart-libpng
 --disable-randr-link
 --disable-kde4

distro-configs/LibreOfficeMacOSX.conf

@@ -12,4 +12,5 @@
 --enable-ext-nlpsolver
 --enable-ext-postgresql-sdbc
 --enable-extension-integration
+--enable-online-update
 --without-system-postgresql

distro-configs/LibreOfficeWin32.conf

@@ -17,3 +17,4 @@
 --enable-ext-pdfimport
 --enable-ext-nlpsolver
 --enable-ext-postgresql-sdbc
+--enable-online-update