Fix #2423, avoid use of abspath make function

The abspath function does not work in GNU make v3.80, which is still
used as it is packaged with the Wind River tools as part of VxWorks 6.x.

The $(abspath ...) function was used in two places related to generating
tables - first for extraction of the ELF file from an intermediate
lib, second for conversion of that ELF file to a table file.  In the
first case, the path should already be absolute, as it comes from CMake.
In the second case, the path should always be relative, because it is
intended to match another pattern rule starting with "elf/%".  For the
second rule, prefixing with $(CURDIR) should achieve the same effect.

cmake/tables/elf2cfetbl_rules.mk

@@ -1,5 +1,10 @@
 # Rule for traditional CFE table generation via elf2cfetbl
 
+# The dependency of this target should always be an absolute pathname to
+# the intermediate library file as it is generated by a CMake script via
+# the TARGET_FILE property.  Therefore, the same path should still work
+# after the "cd" command.  The "cd" is so the ar tool writes the object file
+# into a separate dir, in case of similarly-named files on different cpus.
 elf/%:
-	@mkdir -pv $(dir $(@))
-	cd $(dir $(@)) && $(AR) x $(abspath $(<)) $(notdir $(@))
+	@mkdir -pv "$(dir $(@))"
+	cd "$(dir $(@))" && $(AR) x "$(<)" "$(notdir $(@))"

cmake/tables/tabletool_rule.mk

@@ -4,7 +4,12 @@
 cfetables:
 	@echo "Table build completed"
 
-#%.tbl: $(TBLTOOL)
+# The dependency of this rule should always be a relative path starting with elf/,
+# at least with the current rule generator script, so it matches the elf/% pattern rule.
+# But because elf2cfetbl only writes its output to the current working dir, it has to be run
+# after changing dirs into the staging area.  Thus the path to the elf file needs to be adjusted.
+# Ideally this chould be done with the $(abspath f...) function but this doesn't exist in older versions.
+# As a workaround, $CURDIR is used.
 staging/%.tbl:
-	@mkdir -pv $(dir $(@))
-	cd $(dir $(@)) && $(TBLTOOL) $(TBLTOOL_FLAGS) $(abspath $(^))
+	@mkdir -pv "$(dir $(@))"
+	cd "$(dir $(@))" && $(TBLTOOL) $(TBLTOOL_FLAGS) "$(CURDIR)/$(<)"