Because of gcc -Wmissing-prototypes, all functions in dynamically
loadable modules must have a separate prototype declaration. This is
meant to detect global functions that are not declared in header files,
but in cases where the function is called via dfmgr, this is redundant.
Besides filling up space with boilerplate, this is a frequent source of
compiler warnings in extension modules.
We can fix that by creating the function prototype as part of the
PG_FUNCTION_INFO_V1 macro, which such modules have to use anyway. That
makes the code of modules cleaner, because there is one less place where
the entry points have to be listed, and creates an additional check that
functions have the right prototype.
Remove now redundant prototypes from contrib and other modules.
The original coding examined the next character before verifying that
there *is* a next character. In the worst case with the input buffer
right up against the end of memory, this would result in a segfault.
Problem spotted by Paul Guyot; this commit extends his patch to fix an
additional case. In addition, make the code a tad more readable by not
overloading the usage of *tlen.
