The relevant portion of the log appears to be:
:info:destroot ./gh.texi:1000: must be after `@deftypefun' to use `@deftypefunx'
:info:destroot ./fdl.texi:411: raising the section level of @appendixsubsec which is too low
:info:destroot ./api-utility.texi:566: warning: node `C Hooks' is next for `Hook Reference' in menu but not in sectioning
:info:destroot ./api-utility.texi:674: warning: node `Hook Reference' is prev for `C Hooks' in menu but not in sectioning
:info:destroot ./api-options.texi:510: warning: node next `Printing options' in menu `Debugger options' and in sectioning `Evaluator options' differ
:info:destroot ./api-options.texi:533: warning: node prev `Evaluator options' in menu `Debugger options' and in sectioning `Printing options' differ
:info:destroot ./api-options.texi:544: warning: node next `Evaluator trap options' in menu `Examples of option use' and in sectioning `Debugger options' differ
:info:destroot ./api-options.texi:625: warning: node next `Debugger options' in menu `Evaluator options' and in sectioning `Examples of option use' differ
:info:destroot ./api-options.texi:625: warning: node prev `Debugger options' in menu `Printing options' and in sectioning `Evaluator trap options' differ
:info:destroot ./api-options.texi:681: warning: node prev `Examples of option use' in menu `Evaluator trap options' and in sectioning `Debugger options' differ
:info:destroot make[2]: *** [guile.info] Error 1
This makes it sound like a texinfo problem. texinfo was updated to version 6 last month in r138717; it's possible guile18's use of texinfo is not compatible with texinfo 6 and needs to be patched in some way.
Actually, according to this gentoo bug, it's an incompatibility with texinfo 5 already: https://bugs.gentoo.org/show_bug.cgi?id=464044
Also a debian bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=738295
These have patches attached that we might use.
