json BUGFIX in lyjson_number

The minus sign was taken as part of the number, which is not correct
in this expression.
diff --git a/src/json.c b/src/json.c
index 3ff49c9..2ef1b5a 100644
--- a/src/json.c
+++ b/src/json.c
@@ -428,7 +428,7 @@
                 /* adding zeros at the end */
                 num_len = exponent + e_val;
                 dp_position = num_len; /* decimal point is behind the actual value */
-            } else if ((size_t)labs(e_val) < exponent) {
+            } else if ((size_t)labs(e_val) < (exponent - minus)) {
                 /* adding decimal point between the integer's digits */
                 num_len = exponent + 1;
                 dp_position = exponent + e_val;