Support running checks against a .pkg installation (#23)

Context: dotnet/android#3644

dotnet/android#3644 introduces an Azure Pipelines job to run
API compatibility checks against an installed `.pkg` file that was
produced by a previous step in the build pipeline.  This new check
appears to be failing due to the fact that our installer includes
`Mono.Android.Export.dll` and `OpenTK-1.0.dll` in the *first* target
framework directory that it creates rather than all of them.

We'll now check the first target framework directory for these
relevant assemblies, and only attempt to use the latest if the first
doesn't exist to address this, which would happen on PR builds.

An additional check has also been added to ensure that every expected
API info file is successfully created, regardless of content.

Author: pjcollins

Makefile

@@ -18,6 +18,7 @@ endif  # ndef XA_FRAMEWORK_DIR
 
 STABLE_FRAMEWORKS     = $(shell ls -1 "$(XA_FRAMEWORK_DIR)" | sort -n)
 LAST_STABLE_FRAMEWORK = $(lastword $(STABLE_FRAMEWORKS))
+FIRST_STABLE_FRAMEWORK = $(firstword $(STABLE_FRAMEWORKS))
 
 all: check
 
@@ -70,8 +71,9 @@ CORE_ASSEMBLIES = \
 	Java.Interop                                        \
 	Xamarin.Android.NUnitLite
 
-TFV_ASSEMBLIES = \
-	Mono.Android                                        \
+TFV_ASSEMBLY = Mono.Android
+
+ACCESSORY_TFV_ASSEMBLIES = \
 	Mono.Android.Export                                 \
 	OpenTK-1.0
 
@@ -80,20 +82,29 @@ define BUILD_API_INFO
 	mkdir -p $(1)
 	for file in $(CORE_ASSEMBLIES); do \
 		$(MONO_API_INFO) $(MONO_API_INFO_LIB_DIRS) \
-			$(2)/v1.0/$$file.dll -o=$(1)/$$file.xml & \
+			"$(2)/v1.0/$$file.dll" -o=$(1)/$$file.xml & \
 	done ; \
 	wait
-	for file in $(TFV_ASSEMBLIES) ; do \
-		$(MONO_API_INFO) $(MONO_API_INFO_LIB_DIRS) \
-			$(2)/$(LAST_STABLE_FRAMEWORK)/$$file.dll -o=$(1)/$$file.xml & \
+	$(MONO_API_INFO) $(MONO_API_INFO_LIB_DIRS) \
+		"$(2)/$(LAST_STABLE_FRAMEWORK)/$(TFV_ASSEMBLY).dll" "-o=$(1)/$(TFV_ASSEMBLY).xml" & \
+	for file in $(ACCESSORY_TFV_ASSEMBLIES) ; do \
+		accessoryTfvDir="$(2)/$(FIRST_STABLE_FRAMEWORK)"; \
+		if [ ! -d "$$accessoryTfvDir" ]; then \
+			accessoryTfvDir="$(2)/$(LAST_STABLE_FRAMEWORK)"; \
+		fi; \
+		$(MONO_API_INFO) $(MONO_API_INFO_LIB_DIRS) "$$accessoryTfvDir/$$file.dll" "-o=$(1)/$$file.xml" & \
 	done ; \
 	wait
 endef
 
 check: check-inter-api-level
 	$(call BUILD_API_INFO,temp,$(XA_FRAMEWORK_DIR))
 	failed=0 ; \
-	for file in $(CORE_ASSEMBLIES) $(TFV_ASSEMBLIES) ; do \
+	for file in $(CORE_ASSEMBLIES) $(TFV_ASSEMBLY) $(ACCESSORY_TFV_ASSEMBLIES); do \
+		if [ ! -s temp/$$file.xml ]; then \
+			echo "temp/$$file.xml was not generated."; \
+			failed=1; \
+		fi; \
 		if $(MONO_API_HTML) $(REFERENCE_DIR)/$$file.xml temp/$$file.xml --ignore-changes-parameter-names --ignore-nonbreaking | grep '\<data-is-breaking>' > /dev/null 2>&1 ; then \
 			echo "ABI BREAK IN: $$file.dll" ; \
 			$(MONO_API_HTML) $(REFERENCE_DIR)/$$file.xml temp/$$file.xml  --ignore-changes-parameter-names --ignore-nonbreaking \