libpackage_build: Fix build on gcc2 haiku.

- gcc2 lacks the -iquote option, and side effects of some of the other flags
  we use with it during the build cause some of libcurl's includes to fail.
  This temporarily works around the problem until gcc2 can be suitably fixed.

src/build/libpackage/Jamfile

@@ -81,6 +81,12 @@ HPKG_SOURCES =
 	ZlibDecompressor.cpp
 ;
 
+# TODO: remove this hack once gcc2 has -iquote implemented
+if $(HOST_PLATFORM) = haiku_host &&  $(HOST_GCC_VERSION[1]) < 3 {
+	local locations = common/non-packaged common system ;
+	SourceHdrs FetchFileJob.cpp : /boot/$(locations)/develop/headers/curl ;
+}
+
 # locate the library
 MakeLocate libpackage_build.so : $(HOST_BUILD_COMPATIBILITY_LIB_DIR) ;