This is the version of srcdir.mk that gets used when you build in

the source tree. In contrast, when you build in a separate build tree,

you use a version of srcdir.mk that Configure created, which sets SRCDIR

to the location of the source tree.

This is designed to be included by the top level make file, with

SRCDIR being passed to all the submakes. That means that when you

build in a separate build tree, you must build from the top; you

can't go into a subdirectory and type "make". When you build in the

source tree, local makes work because every local make file checks

whether SRCDIR is set, and if it isn't, sets it with the assumption

that the build directory and source directory are the same.

SRCDIR = $(CURDIR)