add variant for building RTREE module (#12668)

var/spack/repos/builtin/packages/sqlite/package.py

@@ -33,6 +33,8 @@ class Sqlite(AutotoolsPackage):
             description='Enable FTS support '
             '(unsafe for <3.26.0.0 due to Magellan).')
 
+    variant('rtree', default=False, description='Build with Rtree module')
+
     # See https://blade.tencent.com/magellan/index_en.html
     conflicts('+fts', when='@:3.25.99.99')
 
@@ -100,6 +102,10 @@ def configure_args(self):
         if '+fts' not in self.spec:
             args.extend(['--disable-fts4', '--disable-fts5'])
 
+        # Ref: https://sqlite.org/rtree.html
+        if '+rtree' in self.spec:
+            args.append('CPPFLAGS=-DSQLITE_ENABLE_RTREE=1')
+
         return args
 
     @run_after('install')