package: system: ca-certificates: add alternatives

This two packages are meant to be installed side-by-side,add a
semi-dummy ALTERNATIVES field to tell apk to make their provide name
"ca-certs" a virtual(non-versioned) name.

Assign a higher priority to ca-bundle since it is the prefered method
for store certificades[1]. (apk will select ca-bundle lexicographically
if two provider have the same priority, but it is a good example of how
the alternative priority can be used for provider-priority)
(DEFAULT_VARIANT would be a bit forced here)

[1]: dd29980 ("ca-certificates: provide ca-certs by both ca-certificates and ca-bundle")

Signed-off-by: Mario Andrés Pérez <mapb_@outlook.com>

Author: map-b

package/system/ca-certificates/Makefile

@@ -30,6 +30,7 @@ define Package/ca-certificates
   TITLE:=System CA certificates
   PKGARCH:=all
   PROVIDES:=ca-certs
+  ALTERNATIVES:=100:/etc/ssl/certs/__ca-certificates.alternatives:/dev/null
 endef
 
 define Package/ca-bundle
@@ -38,6 +39,7 @@ define Package/ca-bundle
   TITLE:=System CA certificates as a bundle
   PKGARCH:=all
   PROVIDES:=ca-certs
+  ALTERNATIVES:=200:/etc/ssl/certs/__ca-bundle.alternatives:/dev/null
 endef
 
 define Build/Install