Changed top-level Makefile behavior so that BUILDDIR is interpreted

as relative to top-level directory. This done is by abspath'ing it before
passing it to subdirectory Makefile's.

The old behavior had two cases: with and without BUILDDIR being set by
the user. With BUILDDIR not set, the build dir would be named "build"
in the top-level directory. If BUILDDIR was set, then the build dir
would be placed at "src/${BUILDDIR}".

The new behavior is simpler, if BUILDDIR is not set then it defaults
to "build", and the directory holding the final build is always at just
"${BUILDDIR}" in the top level.


[ROCm/rccl-tests commit: bc5f7cfb0a]

projects/rccl-tests/Makefile

@@ -4,6 +4,9 @@
 # See LICENCE.txt for license information
 #
 
+BUILDDIR ?= build
+override BUILDDIR := $(abspath $(BUILDDIR))
+
 .PHONY : all clean
 
 default : src.build
@@ -14,7 +17,7 @@ all:   ${TARGETS:%=%.build}
 clean: ${TARGETS:%=%.clean}
 
 %.build:
-	${MAKE} -C $* build
+	${MAKE} -C $* build BUILDDIR=${BUILDDIR}
 
 %.clean:
-	${MAKE} -C $* clean
+	${MAKE} -C $* clean BUILDDIR=${BUILDDIR}