Fix XML file metaversioning logic.

* define libvintf metaversion at VintfObject::kMetaVersion.
* libvintf@x.y should be able to read all XML files at
  version x.z, where y >= z.
* The minor version of compatibility-matrix.version now means
  the minimum libvintf metaversion that can parse this file.

This CL does not change any behavior on existing XML files
at version 1.0.

Test: libvintf_test
Test: vintf_object_test
Bug: 62801658
Change-Id: If1b74ef83e56565a715e50786a7531ed086755f7
diff --git a/CompatibilityMatrix.cpp b/CompatibilityMatrix.cpp
index f320861..73d0384 100644
--- a/CompatibilityMatrix.cpp
+++ b/CompatibilityMatrix.cpp
@@ -22,8 +22,6 @@
 namespace android {
 namespace vintf {
 
-constexpr Version CompatibilityMatrix::kVersion;
-
 bool CompatibilityMatrix::add(MatrixHal &&hal) {
     return HalGroup<MatrixHal>::add(std::move(hal));
 }
@@ -40,6 +38,11 @@
     return mType;
 }
 
+Version CompatibilityMatrix::getMinimumMetaVersion() const {
+    // TODO(b/62801658): this needs to depend on whether there are 1.1 requirements
+    // (e.g. required <xmlfile> entry)
+    return {1, 0};
+}
 
 status_t CompatibilityMatrix::fetchAllInformation(const std::string &path) {
     return details::fetchAllInformation(path, gCompatibilityMatrixConverter, this);