Fix a linker issue with FIS on Android where the wrong STL was specified. (#265)

Author: jonsimantov

installations/build.gradle

@@ -30,6 +30,11 @@ allprojects {
 
 apply plugin: 'com.android.library'
 
+ext {
+  firebaseAndroidStl = System.getenv('FIREBASE_ANDROID_STL')
+  firebaseAndroidStl = firebaseAndroidStl != null ? firebaseAndroidStl : ''
+}
+
 android {
   compileSdkVersion 28
   buildToolsVersion '28.0.3'
@@ -67,7 +72,8 @@ android {
         //           Only include needed project.
         arguments '-DFIREBASE_CPP_USE_PRIOR_GRADLE_BUILD=ON',
                 '-DFIREBASE_INCLUDE_LIBRARY_DEFAULT=OFF',
-                '-DFIREBASE_INCLUDE_INSTALLATIONS=ON'
+                '-DFIREBASE_INCLUDE_INSTALLATIONS=ON',
+                "-DFIREBASE_ANDROID_STL=${firebaseAndroidStl}"
       }
     }
   }
@@ -80,6 +86,7 @@ android {
 dependencies {
   implementation project(':app')
 }
+apply from: "$rootDir/android_build_files/android_abis.gradle"
 apply from: "$rootDir/android_build_files/generate_proguard.gradle"
 project.afterEvaluate {
   generateProguardFile('installations')

release_build_files/readme.md

@@ -559,6 +559,11 @@ code.
 
 ## Release Notes
 
+### 7.0.1
+-   Changes
+    -   Installations (Android): Fix incorrect STL variants, which fixes
+        a linker error on Android.
+
 ### 7.0.0
 -   Changes
     -   General (iOS): iOS SDKs are now built using Xcode 11.7.