pmb.helpers.package.check_arch(): split (!1776)

Split the part that actually checks the arch against the arches list
into pmb.helpers.pmaports.check_arches(arches, arch), and call it
from pmb.helpers.package.check_arch(args, pkgname, arch, binary).

This will be used in a follow up commit, where we have already resolved
the package data and only need to check the architecture.

pmb/helpers/package.py

@@ -164,13 +164,7 @@ def check_arch(args, pkgname, arch, binary=True):
         arches = get(args, pkgname, arch)["arch"]
     else:
         arches = pmb.helpers.pmaports.get(args, pkgname)["arch"]
-
-    if "!" + arch in arches:
-        return False
-    for value in [arch, "all", "noarch"]:
-        if value in arches:
-            return True
-    return False
+    return pmb.helpers.pmaports.check_arches(arches, arch)
 
 
 def check_arch_recurse(args, pkgname, arch):

pmb/helpers/pmaports.py

@@ -166,3 +166,20 @@ def get_repo(args, pkgname, must_exist=True):
     if not aport:
         return None
     return os.path.basename(os.path.dirname(aport))
+
+
+def check_arches(arches, arch):
+    """ Check if building for a certain arch is allowed.
+
+        :param arches: list of all supported arches, as it can be found in the
+                       arch="" line of APKBUILDS (including all, noarch,
+                       !arch, ...). For example: ["x86_64", "x86", "!armhf"]
+        :param arch: the architecture to check for
+        :returns: True when building is allowed, False otherwise
+    """
+    if "!" + arch in arches:
+        return False
+    for value in [arch, "all", "noarch"]:
+        if value in arches:
+            return True
+    return False