Only attempt to build BeOS code on BeOS (don't even try building an empty

object file elsewhere).

configure.in

@@ -208,6 +208,7 @@ AC_CHECK_FUNCS([memset strrchr])
 dnl Add Makefile conditionals
 AM_CONDITIONAL(BUILD_ZLIB, test x$enable_internal_zlib = xyes)
 AM_CONDITIONAL(BUILD_TEST_PHYSFS, test x$enable_testprog = xyes)
+AM_CONDITIONAL(BUILD_BEOS_CPP, test x$this_is_beos = xyes)
 
 AC_OUTPUT([
 Makefile

platform/Makefile.am

@@ -2,14 +2,20 @@ noinst_LTLIBRARIES = libplatform.la
 
 INCLUDES = -I$(top_srcdir)
 
+if BUILD_BEOS_CPP
+  X = beos.cpp
+else
+  Y = beos.cpp
+endif
+
 libplatform_la_SOURCES =	\
 	unix.c                  \
 	posix.c                 \
-	beos.cpp
+	$(X)
 
 EXTRA_DIST =      \
 	skeleton.c    \
 	macclassic.c  \
-	win32.c
-
+	win32.c       \
+	$(Y)