meson: remove checks for optional libraries

Very few libraries in DPDK are marked as optional.
For SPDK when most of the drivers are disabled,
the requirements are much lower.

By removing the check for optional libraries,
it is possible to pass a narrow set of actually required
libraries.

Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-on: https://review.spdk.io/c/spdk/dpdk/+/25891 (spdk-25.03)

(cherry picked from commit 792dc98)
Change-Id: I60fbc7307a4f33482025a3b3c00948c091d236ff
Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@nutanix.com>
Reviewed-on: https://review.spdk.io/c/spdk/dpdk/+/26630
Reviewed-by: Konrad Sztyber <ksztyber@nvidia.com>
Reviewed-by: Jim Harris <jim.harris@nvidia.com>
Tested-by: Tomasz Zawadzki <tomasz@tzawadzki.com>

Author: tomzawadzki

lib/meson.build

@@ -157,12 +157,8 @@ foreach l:libraries
         build = false
         reason = 'not in enabled libraries build config'
     elif disable_libs.contains(l)
-        if always_enable.contains(l)
-            warning('Cannot disable mandatory library "@0@"'.format(l))
-        else
-            build = false
-            reason = 'explicitly disabled via build config'
-        endif
+        build = false
+        reason = 'explicitly disabled via build config'
     endif
 
     if build