minor - fix analytics_build_info

[underhood]

Summary

While doing other stuff (which will use output of this function) I noticed analytics_build_info() will produce wrong output if db-engine is not compiled in.
This fixes it with macro and removes related TODO comment.

Any decent compiler will remove the conditional jump (related to first variable) as its value is known at compile time in every case (conflating it to just the needed buffer_strcat calls without ifs). Sample from gcc:

gdb disassemble

   0x000000000041248b <+79>:    mov    $0x83a475,%esi
   0x0000000000412490 <+84>:    mov    %rbx,%rdi
   0x0000000000412493 <+87>:    call   0x42444c <buffer_strcat>
   0x0000000000412498 <+92>:    mov    $0x83a489,%esi
   0x000000000041249d <+97>:    mov    %rbx,%rdi
   0x00000000004124a0 <+100>:   call   0x42444c <buffer_strcat>
   0x00000000004124a5 <+105>:   mov    $0x83a493,%esi
   0x00000000004124aa <+110>:   mov    %rbx,%rdi
   0x00000000004124ad <+113>:   call   0x42444c <buffer_strcat>
   0x00000000004124b2 <+118>:   mov    $0x83a49b,%esi
   0x00000000004124b7 <+123>:   mov    %rbx,%rdi
   0x00000000004124ba <+126>:   call   0x42444c <buffer_strcat>
   0x00000000004124bf <+131>:   mov    $0x83a4a6,%esi
   0x00000000004124c4 <+136>:   mov    %rbx,%rdi
   0x00000000004124c7 <+139>:   call   0x42444c <buffer_strcat>
   0x00000000004124cc <+144>:   mov    $0x83a4ac,%esi
   0x00000000004124d1 <+149>:   mov    %rbx,%rdi
   0x00000000004124d4 <+152>:   call   0x42444c <buffer_strcat>
   0x00000000004124d9 <+157>:   mov    $0x83a4b2,%esi
   0x00000000004124de <+162>:   mov    %rbx,%rdi
   0x00000000004124e1 <+165>:   call   0x42444c <buffer_strcat>
   0x00000000004124e6 <+170>:   mov    $0x83a4b8,%esi
   0x00000000004124eb <+175>:   mov    %rbx,%rdi
   0x00000000004124ee <+178>:   call   0x42444c <buffer_strcat>
   0x00000000004124f3 <+183>:   mov    $0x83a4d1,%esi
   0x00000000004124f8 <+188>:   mov    %rbx,%rdi
   0x00000000004124fb <+191>:   call   0x42444c <buffer_strcat>
   0x0000000000412500 <+196>:   mov    $0x83a4d7,%esi
   0x0000000000412505 <+201>:   mov    %rbx,%rdi
   0x0000000000412508 <+204>:   call   0x42444c <buffer_strcat>
   0x000000000041250d <+209>:   mov    $0x83a4dd,%esi
   0x0000000000412512 <+214>:   mov    %rbx,%rdi
   0x0000000000412515 <+217>:   call   0x42444c <buffer_strcat>

Test Plan

Build agent without dbengine. Output of curl 127.0.0.1:19999/api/v1/info | jq .buildinfo should not start with |

Before |Native HTTPS|Netdata Cloud..., after Native HTTPS|Netdata Cloud...

Additional Information

[MrZammler]

Thanks Timo.