build: remove build stubs for external leveldb

Presumably these stubs indicate to packagers that external leveldb is meant to
be supported in some way. It is not. Remove the stubs to avoid sending any
mixed messages.

Author: theuni

configure.ac

@@ -1225,14 +1225,6 @@ if test "x$have_any_system" != "xno"; then
   AC_DEFINE(HAVE_SYSTEM, 1, Define to 1 if std::system or ::wsystem is available.)
 fi
 
-LEVELDB_CPPFLAGS=
-LIBLEVELDB=
-LIBMEMENV=
-AM_CONDITIONAL([EMBEDDED_LEVELDB],[true])
-AC_SUBST(LEVELDB_CPPFLAGS)
-AC_SUBST(LIBLEVELDB)
-AC_SUBST(LIBMEMENV)
-
 dnl SUPPRESSED_CPPFLAGS=SUPPRESS_WARNINGS([$SOME_CPPFLAGS])
 dnl Replace -I with -isystem in $SOME_CPPFLAGS to suppress warnings from
 dnl headers from its include directories and return the result.

src/Makefile.am

@@ -852,11 +852,8 @@ nodist_libbitcoin_ipc_a_SOURCES = $(libbitcoin_ipc_mpgen_output)
 CLEANFILES += $(libbitcoin_ipc_mpgen_output)
 endif
 
-if EMBEDDED_LEVELDB
 include Makefile.crc32c.include
 include Makefile.leveldb.include
-endif
-
 include Makefile.test_util.include
 include Makefile.test_fuzz.include
 

src/Makefile.leveldb.include

@@ -8,9 +8,10 @@ LIBMEMENV_INT  = leveldb/libmemenv.a
 EXTRA_LIBRARIES += $(LIBLEVELDB_INT)
 EXTRA_LIBRARIES += $(LIBMEMENV_INT)
 
-LIBLEVELDB += $(LIBLEVELDB_INT) $(LIBCRC32C)
-LIBMEMENV += $(LIBMEMENV_INT)
+LIBLEVELDB = $(LIBLEVELDB_INT) $(LIBCRC32C)
+LIBMEMENV = $(LIBMEMENV_INT)
 
+LEVELDB_CPPFLAGS =
 LEVELDB_CPPFLAGS += -I$(srcdir)/leveldb/include
 LEVELDB_CPPFLAGS += -I$(srcdir)/leveldb/helpers/memenv