[m-rev.] Fix race conditions for the 'depend' make target.

[Paul Bone]

Fix the race conditions in the deep_profiler and slice directories when they
copy the mdbcomp files in.

deep_profiler/Mmakefile:
slice/Mmakefile:
    As above.
---
 deep_profiler/Mmakefile |   13 +++++++++++--
 slice/Mmakefile         |   13 +++++++++++--
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/deep_profiler/Mmakefile b/deep_profiler/Mmakefile
index c43fc09..1ab7af8 100644
--- a/deep_profiler/Mmakefile
+++ b/deep_profiler/Mmakefile
@@ -121,17 +121,26 @@ Mercury.modules: DEEP_FLAGS
 .PHONY: all
 all:	$(MDBCOMP_MODULES) $(ALL_DEEP_MODULES) $(TAGS_FILE_EXISTS)
 
+# We use the sentinel file .mdbcomp_modules to avoid the race condition that
+# exists because the rule would normally be invoked for each of the mdbcomp
+# modules.  Note that a .PHONY target does not work.  However, we also need
+# to use the no-op action '@' to allow make to see that the timestamps on
+# the $(MDBCOMP_MODULES) have changed and that other things may need
+# rebuilding.
+$(MDBCOMP_MODULES): .mdbcomp_modules
+	@
+
 # We need to start by turning write permission on for each copied file
 # in case some exist, but we need to ignore errors in case some don't exist.
 # The exit 0 is to prevent make itself from printing a message about the
 # (ignored) failure of an action.
 #
 # We could modify the action here to copy only the changed files.
-
-$(MDBCOMP_MODULES): $(MDBCOMP_ORIG_MODULES)
+.mdbcomp_modules : $(MDBCOMP_ORIG_MODULES)
 	- at chmod a+w $(MDBCOMP_MODULES) > /dev/null 2>&1; exit 0
 	cp $(MDBCOMP_ORIG_MODULES) .
 	@chmod a-w $(MDBCOMP_MODULES)
+	touch $@
 
 #-----------------------------------------------------------------------------#
 
diff --git a/slice/Mmakefile b/slice/Mmakefile
index cdfca10..4366d36 100644
--- a/slice/Mmakefile
+++ b/slice/Mmakefile
@@ -91,17 +91,26 @@ all:	$(MDBCOMP_MODULES) $(MERCURY_MAIN_MODULES) $(TAGS_FILE_EXISTS)
 
 #-----------------------------------------------------------------------------#
 #
+# We use the sentinel file .mdbcomp_modules to avoid the race condition that
+# exists because the rule would normally be invoked for each of the mdbcomp
+# modules.  Note that a .PHONY target does not work.  However, we also need
+# to use the no-op action '@' to allow make to see that the timestamps on
+# the $(MDBCOMP_MODULES) have changed and that other things may need
+# rebuilding.
+$(MDBCOMP_MODULES): .mdbcomp_modules
+	@
+
 # We need to start by turning write permission on for each copied file
 # in case some exist, but we need to ignore errors in case some don't exist.
 # The exit 0 is to prevent make itself from printing a message about the
 # (ignored) failure of an action.
 #
 # We could modify the action here to copy only the changed files.
-
-$(MDBCOMP_MODULES): $(MDBCOMP_ORIG_MODULES)
+.mdbcomp_modules : $(MDBCOMP_ORIG_MODULES)
 	- at chmod a+w $(MDBCOMP_MODULES) > /dev/null 2>&1; exit 0
 	cp $(MDBCOMP_ORIG_MODULES) .
 	@chmod a-w $(MDBCOMP_MODULES)
+	touch $@
 
 #-----------------------------------------------------------------------------#
 
-- 
1.7.2.5