tools/memory-model: Make history-check scripts use mselect7

The history-check scripts currently use grep to ignore non-C-language
litmus tests, which is a bit fragile.  This commit therefore enlists the
aid of "mselect7 -arch C", given Luc Maraget's recent modifications that
allow mselect7 to operate in filter mode.

This change requires herdtools 7.52-32-g1da3e0e50977 or later.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/memory-model/scripts/initlitmushist.sh

@@ -60,7 +60,7 @@ fi
 
 # Create a list of the C-language litmus tests with no more than the
 # specified number of processes (per the --procs argument).
-find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C
+find litmus -name '*.litmus' -print | mselect7 -arch C > $T/list-C
 xargs < $T/list-C -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
 
 scripts/runlitmushist.sh < $T/list-C-short

tools/memory-model/scripts/newlitmushist.sh

@@ -43,7 +43,7 @@ fi
 
 # Form full list of litmus tests with no more than the specified
 # number of processes (per the --procs argument).
-find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C-all
+find litmus -name '*.litmus' -print | mselect7 -arch C > $T/list-C-all
 xargs < $T/list-C-all -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
 
 # Form list of new tests.  Note: This does not handle litmus-test deletion!