build: degradation on src/box/sql/libsql build after commit a33108a "sql: fix mem_apply_type double type truncation"

[avtikhon]

Tarantool version:
Commit a33108a
"sql: fix mem_apply_type double type truncation"

OS version:
Debian Buster + ASAN + Clang8

Bug description:
https://gitlab.com/tarantool/tarantool/-/jobs/588714883

 [100%] Built target merger.test
 /usr/bin/ld: ../../src/box/sql/libsql.a(build.c.o): in function `vdbe_emit_fk_constraint_create':
 /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1061: undefined reference to `fk_constraint_match_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1063: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1065: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: ../../src/box/sql/libsql.a(pragma.c.o): in function `sql_pragma_foreign_key_list':
 /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/pragma.c:308: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/pragma.c:310: undefined reference to `fk_constraint_action_strs'
 clang: error: linker command failed with exit code 1 (use -v to see invocation)
 make[4]: Leaving directory '/builds/pUzQszzd/0/tarantool/tarantool'
 make[4]: *** [test/unit/CMakeFiles/luaT_tuple_new.test.dir/build.make:141: test/unit/luaT_tuple_new.test] Error 1
 make[3]: *** [CMakeFiles/Makefile2:8112: test/unit/CMakeFiles/luaT_tuple_new.test.dir/all] Error 2
 make[3]: *** Waiting for unfinished jobs....
 /usr/bin/ld: box/sql/libsql.a(build.c.o): in function `vdbe_emit_fk_constraint_create':
 /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1061: undefined reference to `fk_constraint_match_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1063: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/build.c:1065: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: box/sql/libsql.a(pragma.c.o): in function `sql_pragma_foreign_key_list':
 /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/pragma.c:308: undefined reference to `fk_constraint_action_strs'
 /usr/bin/ld: /builds/pUzQszzd/0/tarantool/tarantool/src/box/sql/pragma.c:310: undefined reference to `fk_constraint_action_strs'
 clang: error: linker command failed with exit code 1 (use -v to see invocation)
 make[4]: *** [src/CMakeFiles/tarantool.dir/build.make:191: src/tarantool] Error 1
 make[4]: Leaving directory '/builds/pUzQszzd/0/tarantool/tarantool'
 make[3]: *** [CMakeFiles/Makefile2:2108: src/CMakeFiles/tarantool.dir/all] Error 2
 make[3]: Leaving directory '/builds/pUzQszzd/0/tarantool/tarantool'
 make[2]: *** [Makefile:152: all] Error 2
 make[2]: Leaving directory '/builds/pUzQszzd/0/tarantool/tarantool'
 make[1]: *** [.travis.mk:117: build_asan_debian] Error 2
 make[1]: Leaving directory '/builds/pUzQszzd/0/tarantool/tarantool'
 make: *** [.gitlab.mk:18: test_asan_debian_no_deps] Error 2
 ERROR: Job failed: exit code 1

Steps to reproduce:

Optional (but very desirable):

• coredump
• backtrace
• netstat

[Gerold103]

The commit clearly not related to the bug, it existed always. But somewhy didn't reveal itself. Seems like SQL library is totally broken - it heavily depends on box library and its symbols, but does not link with it. Instead, it waits until box will include it. This somehow worked before, but when UB sanitizer is on, it seems something is being built or linked a little differently. Although I couldn't find what exactly, so far.
luaT_tuple_new.test build perfectly fine if you use ENABLE_UB_SANITIZER=OFF, but fails when it is one. When I turned VERBOSE=1, I saw, that the target build command is exactly the same in both cases (not counting -fsanitize flags).
Perhaps we should remove sql library, and build sql sources inside box library. Anyway they depend on each other.