Fix: (org-ql-view--expand-buffers-files) Remove eval support

This prevents arbitrary code execution when opening "org-ql-search:"
links.  (The links feature was just pushed to master in the last day
or so, and no stable release with the feature has been tagged.)  This
fix also means that arbitrary expressions are no longer accepted when
interactively completing the buffers-files argument to
org-ql-search (a worthy trade, I think; users who need to do that can
call the function from Lisp).

org-ql.info

@@ -214,7 +214,6 @@ Interactively, may also be:
    • ‘all’: search all Org buffers
    • ‘agenda’: search buffers returned by the function
      ‘org-agenda-files’
-   • An expression which evaluates to a list of files/buffers
    • A space-separated list of file or buffer names
 
    ‘GROUPS’: An ‘org-super-agenda’ group set.  See variable
@@ -1270,43 +1269,43 @@ Node: Quelpa2428
 Node: Usage2871
 Node: Commands3269
 Node: org-ql-search3742
-Node: helm-org-ql5456
-Node: org-ql-view5868
-Node: org-ql-view-sidebar6368
-Node: org-ql-view-recent-items6724
-Node: org-ql-sparse-tree7208
-Node: Queries8008
-Node: Non-sexp query syntax8916
-Node: General predicates10623
-Node: Ancestor/descendant predicates15838
-Node: Date/time predicates16966
-Node: Functions / Macros19621
-Node: Agenda-like views19876
-Node: Listing / acting-on results21281
-Node: Dynamic block25883
-Node: Links28046
-Node: Tips28733
-Node: Changelog29051
-Node: 05-pre29690
-Node: 04630782
-Node: 04531185
-Node: 04431544
-Node: 04331901
-Node: 04232096
-Node: 04132255
-Node: 0432494
-Node: 03236425
-Node: 03136802
-Node: 0336999
-Node: 02339974
-Node: 02240202
-Node: 02140470
-Node: 0240669
-Node: 0144704
-Node: Notes44805
-Node: Comparison with Org Agenda searches44967
-Node: org-sidebar45839
-Node: License46118
+Node: helm-org-ql5392
+Node: org-ql-view5804
+Node: org-ql-view-sidebar6304
+Node: org-ql-view-recent-items6660
+Node: org-ql-sparse-tree7144
+Node: Queries7944
+Node: Non-sexp query syntax8852
+Node: General predicates10559
+Node: Ancestor/descendant predicates15774
+Node: Date/time predicates16902
+Node: Functions / Macros19557
+Node: Agenda-like views19812
+Node: Listing / acting-on results21217
+Node: Dynamic block25819
+Node: Links27982
+Node: Tips28669
+Node: Changelog28987
+Node: 05-pre29626
+Node: 04630718
+Node: 04531121
+Node: 04431480
+Node: 04331837
+Node: 04232032
+Node: 04132191
+Node: 0432430
+Node: 03236361
+Node: 03136738
+Node: 0336935
+Node: 02339910
+Node: 02240138
+Node: 02140406
+Node: 0240605
+Node: 0144640
+Node: Notes44741
+Node: Comparison with Org Agenda searches44903
+Node: org-sidebar45775
+Node: License46054
 
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