build: rename FORCEDEBUG_CPPFLAGS to LIBZPOOL_CPPFLAGS

This is just a very small attempt to make it more obvious that these
flags aren't optional for libzpool-using programs, by not making it seem
like there's an option to say "well, I don't _want_ to force debugging".

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Rich Ercolani <rincebrain@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Issue #16476
Closes #16477

cmd/Makefile.am

@@ -24,7 +24,7 @@ zfs_ids_to_path_LDADD = \
 	libzfs.la
 
 
-zhack_CPPFLAGS = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
+zhack_CPPFLAGS = $(AM_CPPFLAGS) $(LIBZPOOL_CPPFLAGS)
 
 sbin_PROGRAMS   += zhack
 CPPCHECKTARGETS += zhack
@@ -39,7 +39,7 @@ zhack_LDADD = \
 
 
 ztest_CFLAGS    = $(AM_CFLAGS) $(KERNEL_CFLAGS)
-ztest_CPPFLAGS  = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
+ztest_CPPFLAGS  = $(AM_CPPFLAGS) $(LIBZPOOL_CPPFLAGS)
 
 sbin_PROGRAMS   += ztest
 CPPCHECKTARGETS += ztest

cmd/raidz_test/Makefile.am

@@ -1,5 +1,5 @@
 raidz_test_CFLAGS   = $(AM_CFLAGS)   $(KERNEL_CFLAGS)
-raidz_test_CPPFLAGS = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
+raidz_test_CPPFLAGS = $(AM_CPPFLAGS) $(LIBZPOOL_CPPFLAGS)
 
 bin_PROGRAMS    += raidz_test
 CPPCHECKTARGETS += raidz_test

cmd/zdb/Makefile.am

@@ -1,4 +1,4 @@
-zdb_CPPFLAGS = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
+zdb_CPPFLAGS = $(AM_CPPFLAGS) $(LIBZPOOL_CPPFLAGS)
 zdb_CFLAGS   = $(AM_CFLAGS) $(LIBCRYPTO_CFLAGS)
 
 sbin_PROGRAMS   += zdb

cmd/zstream/Makefile.am

@@ -1,4 +1,4 @@
-zstream_CPPFLAGS = $(AM_CPPFLAGS) $(FORCEDEBUG_CPPFLAGS)
+zstream_CPPFLAGS = $(AM_CPPFLAGS) $(LIBZPOOL_CPPFLAGS)
 
 sbin_PROGRAMS   += zstream
 CPPCHECKTARGETS += zstream