Configurations/10-main.conf: force no-engine on ios targets.

Rationale for enforcing no-engine is because of disconnect between
compile-time config and run-time, which is a per-application sandbox
directory which one can't predict in advance. Besides, none of the
bundled engines actually give an edge on iOS...

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6106)

Configurations/10-main.conf

@@ -1592,6 +1592,7 @@ my %targets = (
         inherit_from     => [ "darwin-common" ],
         cflags           => add("-isysroot \$(CROSS_TOP)/SDKs/\$(CROSS_SDK) -fno-common"),
         sys_id           => "iOS",
+        disable          => [ "engine" ],
     },
     "ios-cross" => {
         inherit_from     => [ "darwin-common", asm("armv4_asm") ],
@@ -1601,6 +1602,7 @@ my %targets = (
         cflags           => add("-arch armv7 -mios-version-min=6.0.0 -isysroot \$(CROSS_TOP)/SDKs/\$(CROSS_SDK) -fno-common"),
         sys_id           => "iOS",
         perlasm_scheme   => "ios32",
+        disable          => [ "engine" ],
     },
     "ios64-cross" => {
         inherit_from     => [ "darwin-common", asm("aarch64_asm") ],
@@ -1608,6 +1610,7 @@ my %targets = (
         sys_id           => "iOS",
         bn_ops           => "SIXTY_FOUR_BIT_LONG RC4_CHAR",
         perlasm_scheme   => "ios64",
+        disable          => [ "engine" ],
     },
 
 ##### GNU Hurd