base.bbclass: Add PKGTRIPLETS and PKGMLTRIPLETS variables

[Richard Purdie <richard.purdie@linuxfoundation.org>]

These variables correspond to the PACKAGE_ARCH list combined with the TARGET_VENDOR
and TARGET_OS values. These can be used to traverse the pkgdata structure.

Setting these once in base.bbclass stops pkgdata needing to recalculate the values
and is also useful for the reworked shlibs code in a patch that will follow this.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/meta/classes/base.bbclass b/meta/classes/base.bbclass
index f8efbf9..860f390 100644
--- a/meta/classes/base.bbclass
+++ b/meta/classes/base.bbclass
@@ -334,6 +334,38 @@ do_build () {
 	:
 }
 
+def set_packagetriplet(d):
+    archs = []
+    tos = []
+    tvs = []
+
+    archs.append(d.getVar("PACKAGE_ARCHS", True).split())
+    tos.append(d.getVar("TARGET_OS", True))
+    tvs.append(d.getVar("TARGET_VENDOR", True))
+
+    def settriplet(d, varname, archs, tos, tvs):
+        triplets = []
+        for i in range(len(archs)):
+            for arch in archs[i]:
+                triplets.append(arch + tvs[i] + "-" + tos[i])
+        triplets.reverse()
+        d.setVar(varname, " ".join(triplets))
+
+    settriplet(d, "PKGTRIPLETS", archs, tos, tvs)
+
+    variants = d.getVar("MULTILIB_VARIANTS", True) or ""
+    for item in variants.split():
+        localdata = bb.data.createCopy(d)
+        overrides = localdata.getVar("OVERRIDES", False) + ":virtclass-multilib-" + item
+        localdata.setVar("OVERRIDES", overrides)
+        bb.data.update_data(localdata)
+
+        archs.append(localdata.getVar("PACKAGE_ARCHS", True).split())
+        tos.append(localdata.getVar("TARGET_OS", True))
+        tvs.append(localdata.getVar("TARGET_VENDOR", True))
+
+    settriplet(d, "PKGMLTRIPLETS", archs, tos, tvs)
+
 python () {
     import exceptions, string, re
 
@@ -521,6 +553,8 @@ python () {
     if ".zip" in srcuri:
         d.appendVarFlag('do_unpack', 'depends', ' unzip-native:do_populate_sysroot')
 
+    set_packagetriplet(d)
+
     # 'multimachine' handling
     mach_arch = d.getVar('MACHINE_ARCH', True)
     pkg_arch = d.getVar('PACKAGE_ARCH', True)