The 1.2.x branch and trunk do not support compiling on BeOS with VPATH. On BeOS, @OSDIR@ != @DEFAULT_OSDIR@ and only the build include dir is searched for the default OS (unix). This worked fine in the 0.9.x branch.
Created attachment 21475 [details] proposed patch This path extends the search path by adding the source default OS dir.
Although I got the bug number wrong [marking this blocking so the bug number ca be decoded from the commit) this is fixed on 1.3 and trunk. Thanks!