I propose the attached patches for Emacs 26.3, to help it compile 
cleanly with more-recent software (GCC 9, librsvg 2.45.1). The idea is 
mainly to avoid bug reports from people who would otherwise send us 
these diagnostics. Most of these patches are already in master; the 
exceptions (patches 2 and 5) are for parts of Emacs that are typically 
not compiled in master.