test.mk: don't use a temporary random.bin

Sometimes using a temp file to make test-random.h breaks builds because
clean and test get made in parallel.

Since debugging parallel make is anything but easy, it's better to just
not use the intermediate file.  This patch makes it use a pipe instead.
Because we live in the worst possible world, we have to support RHEL 9,
in which xxd does not support "-n prefix", and so we have to build the
header variable definition lines in shell.

Signed-off-by: Peter Jones <pjones@redhat.com>

Author: vathpela

include/test.mk

@@ -76,8 +76,12 @@ libefi-test.a :
 		clean
 
 test-random.h:
-	dd if=/dev/urandom bs=512 count=17 of=random.bin
-	xxd -i random.bin test-random.h
+	dd if=/dev/urandom bs=512 count=17 status=none | ( \
+		echo "unsigned char random_bin[] = {" ; \
+		xxd -i - ; \
+		echo "};" ; \
+		echo "unsigned int random_bin_len = 8704;" ; \
+	) > test-random.h
 
 $(wildcard test-*.c) :: %.c : test-random.h
 $(patsubst %.c,%,$(wildcard test-*.c)) :: | test-random.h
@@ -119,14 +123,13 @@ test-coverage : CFLAGS_GCOV+=--coverage
 test-coverage : $(tests)
 
 test-clean :
-	@rm -vf test-random.h random.bin libefi-test.a
+	@rm -vf test-random.h libefi-test.a
 	@rm -vf *.gcda *.gcno *.gcov vgcore.*
 
 clean : test-clean
 
 all : test-clean test
 
 .PHONY: $(tests) all test clean
-.SECONDARY: random.bin
 
 # vim:ft=make