Clang static analyser fixes

[ac000]

These commits fix a couple of issues found by the clang static analyser.

• Var: Remove a dead assignment in nxt_var_interpreter()

The first removes a dead assignment whereby we store the return from a nxt_cpymem() bu then return from the function before doing anything further with it.

• Avoid potential NULL pointer dereference in nxt_router_temp_conf()

The second fixes a potential NULL pointer dereference.

[hongzhidao]

LGTM.

And just another way.

    if (rtcf != NULL && rtcf->tstr_state != NULL) {
        nxt_tstr_state_release(rtcf->tstr_state);
    }

Both are ok, fix it in your preferred way.

[ac000]

LGTM.

And just another way.

    if (rtcf != NULL && rtcf->tstr_state != NULL) {
        nxt_tstr_state_release(rtcf->tstr_state);
    }

Both are ok, fix it in your preferred way.

Yes, that also works. However I like the overall goto label clean up which i think improves the whole function...

[ac000]

• Rebased with master
• Added Zhidao's Reviewed-bys

$ git range-diff 532c4bab...c2f7f296
 -:  -------- >  1:  e2cab032 Remove debug from builds and tests
 -:  -------- >  2:  faa7e792 Packages: Pass CFLAGS to compile wasm modules on all packaging targets
 -:  -------- >  3:  9d02b906 Add PHP 8.2 and 8.1 to test matrix
 -:  -------- >  4:  d5665f49 Update setup-go to v5
 -:  -------- >  5:  4d25c612 Edited changes.xml for the 1.32.0 release
 -:  -------- >  6:  ace553dc Generated Dockerfiles for Unit 1.32.0
 -:  -------- >  7:  08811700 Added version 1.32.0 CHANGES
 -:  -------- >  8:  e67d7433 Version bump
 -:  -------- >  9:  23e807de Wasm-wc: use more common uname switch to get operating system name
 -:  -------- > 10:  8ff606fb Configuration: Fix check in nxt_conf_json_parse_value()
 -:  -------- > 11:  4eb008bb Remove unused nxt_vector_t API
 1:  67635d72 ! 12:  353d2d05 Var: Remove a dead assignment in nxt_var_interpreter()
    @@ Commit message
     
         Found by the clang static analyser.
     
    +    Reviewed-by: Zhidao Hong <z.hong@f5.com>
         Signed-off-by: Andrew Clayton <a.clayton@nginx.com>
     
      ## src/nxt_var.c ##
 2:  532c4bab ! 13:  c2f7f296 Avoid potential NULL pointer dereference in nxt_router_temp_conf()
    @@ Commit message
     
         This was found by the clang static analyser.
     
    +    Reviewed-by: Zhidao Hong <z.hong@f5.com>
         Signed-off-by: Andrew Clayton <a.clayton@nginx.com>
     
      ## src/nxt_router.c ##