Tweak new jsonb_plperl test cases to work with old Perl versions.

The previous coding here didn't actually produce Inf or NaN double
values in Perl versions 5.8.x.  Adopt a suggestion from stackoverflow.

Discussion: https://postgr.es/m/28585.1525131438@sss.pgh.pa.us

contrib/jsonb_plperl/expected/jsonb_plperl.out

@@ -43,7 +43,7 @@ CREATE FUNCTION testInf() RETURNS jsonb
 LANGUAGE plperl
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'Inf';
+$val = 9**9**9;  # we assume this will overflow to +Inf
 return $val;
 $$;
 SELECT testInf();
@@ -53,7 +53,7 @@ CREATE FUNCTION testNaN() RETURNS jsonb
 LANGUAGE plperl
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'NaN';
+$val = sin(9**9**9);  # we assume sin(inf) will yield NaN
 return $val;
 $$;
 SELECT testNaN();

contrib/jsonb_plperl/expected/jsonb_plperlu.out

@@ -43,7 +43,7 @@ CREATE FUNCTION testInf() RETURNS jsonb
 LANGUAGE plperlu
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'Inf';
+$val = 9**9**9;  # we assume this will overflow to +Inf
 return $val;
 $$;
 SELECT testInf();
@@ -53,7 +53,7 @@ CREATE FUNCTION testNaN() RETURNS jsonb
 LANGUAGE plperlu
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'NaN';
+$val = sin(9**9**9);  # we assume sin(inf) will yield NaN
 return $val;
 $$;
 SELECT testNaN();

contrib/jsonb_plperl/sql/jsonb_plperl.sql

@@ -38,7 +38,7 @@ CREATE FUNCTION testInf() RETURNS jsonb
 LANGUAGE plperl
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'Inf';
+$val = 9**9**9;  # we assume this will overflow to +Inf
 return $val;
 $$;
 
@@ -49,7 +49,7 @@ CREATE FUNCTION testNaN() RETURNS jsonb
 LANGUAGE plperl
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'NaN';
+$val = sin(9**9**9);  # we assume sin(inf) will yield NaN
 return $val;
 $$;
 

contrib/jsonb_plperl/sql/jsonb_plperlu.sql

@@ -38,7 +38,7 @@ CREATE FUNCTION testInf() RETURNS jsonb
 LANGUAGE plperlu
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'Inf';
+$val = 9**9**9;  # we assume this will overflow to +Inf
 return $val;
 $$;
 
@@ -49,7 +49,7 @@ CREATE FUNCTION testNaN() RETURNS jsonb
 LANGUAGE plperlu
 TRANSFORM FOR TYPE jsonb
 AS $$
-$val = 0 + 'NaN';
+$val = sin(9**9**9);  # we assume sin(inf) will yield NaN
 return $val;
 $$;