Add btree_gin contrib module.

Teodor Sigaev and Oleg Bartunov

contrib/btree_gin/expected/float4.out

@@ -0,0 +1,44 @@
+set enable_seqscan=off;
+CREATE TABLE test_float4 (
+	i float4
+);
+INSERT INTO test_float4 VALUES (-2),(-1),(0),(1),(2),(3);
+CREATE INDEX idx_float4 ON test_float4 USING gin (i);
+SELECT * FROM test_float4 WHERE i<1::float4 ORDER BY i;
+ i  
+----
+ -2
+ -1
+  0
+(3 rows)
+
+SELECT * FROM test_float4 WHERE i<=1::float4 ORDER BY i;
+ i  
+----
+ -2
+ -1
+  0
+  1
+(4 rows)
+
+SELECT * FROM test_float4 WHERE i=1::float4 ORDER BY i;
+ i 
+---
+ 1
+(1 row)
+
+SELECT * FROM test_float4 WHERE i>=1::float4 ORDER BY i;
+ i 
+---
+ 1
+ 2
+ 3
+(3 rows)
+
+SELECT * FROM test_float4 WHERE i>1::float4 ORDER BY i;
+ i 
+---
+ 2
+ 3
+(2 rows)
+