Makefile.inc: Add support for staged builds.

- Allow the RTEMS_ROOT to be conditionally supplied. This
  can be a staging area before being moved to the final
  install prefix location.

- Update the default.cfg to use RTEMS_ROOT and to not rely on
  the exec_prefix so it's paths can be staged.

- Fix and add the needed configure subs.

Closes #3768

c/src/make/Makefile.am

@@ -68,6 +68,8 @@ Makefile.inc: Makefile.inc.in Makefile
 	-e "s|[@]exec_prefix[@]|$(exec_prefix)|" \
 	-e "s|[@]pkgdatadir[@]|$(pkgdatadir)|" \
 	-e "s|[@]RTEMS_BSP[@]|$(RTEMS_BSP)|" \
+	-e "s|[@]RTEMS_CPU[@]|$(RTEMS_CPU)|" \
+	-e "s|[@]RTEMS_API[@]|$(RTEMS_API)|" \
 	-e "s|[@]CC[@]|$(CC)|" \
 	-e "s|[@]CXX[@]|$(CXX)|" \
 	-e "s|[@]AS[@]|$(AS)|" \
@@ -85,4 +87,3 @@ CLEANFILES += Makefile.inc
 ## use gcc-target-default.cfg only.
 rtems_make_compilersdir = $(rtems_makedir)/compilers
 dist_rtems_make_compilers_DATA = compilers/gcc-target-default.cfg
-

c/src/make/Makefile.inc.in

@@ -1,7 +1,13 @@
 #
 # BSP specific settings. To be included in application Makefiles
 #
+# This support will be removed from RTEMS. Please consider other
+# ways to build applications.
+#
 
+RTEMS_API = @RTEMS_API@
+
+RTEMS_CPU = @RTEMS_CPU@
 RTEMS_BSP = @RTEMS_BSP@
 
 prefix = @prefix@
@@ -16,8 +22,6 @@ LD_FOR_TARGET = @LD@
 SIZE_FOR_TARGET = @SIZE@
 OBJCOPY_FOR_TARGET = @OBJCOPY@
 
-RTEMS_API = @RTEMS_API@
-
 CC= $(CC_FOR_TARGET)
 CXX= $(CXX_FOR_TARGET)
 AS= $(AS_FOR_TARGET)
@@ -36,10 +40,10 @@ export AR
 export SIZE
 export OBJCOPY
 
-RTEMS_ROOT = $(prefix)
+RTEMS_ROOT  ?= $(prefix)
 PROJECT_ROOT = $(RTEMS_ROOT)
 RTEMS_CUSTOM = $(RTEMS_ROOT)/make/custom/$(RTEMS_BSP).cfg
-RTEMS_SHARE = $(RTEMS_ROOT)/share/rtems$(RTEMS_API)
+RTEMS_SHARE  = $(RTEMS_ROOT)/share/rtems$(RTEMS_API)
 
 RTEMS_USE_OWN_PDIR = no
 RTEMS_HAS_POSIX_API = @RTEMS_HAS_POSIX_API@
@@ -49,4 +53,3 @@ RTEMS_HAS_CPLUSPLUS = @RTEMS_HAS_CPLUSPLUS@
 export RTEMS_BSP
 export RTEMS_CUSTOM
 export PROJECT_ROOT
-