Omit unneeded decimal points in modp_dtoa2() scientific notation output

For example, "1e-13" is now used instead of "1.e-13".

src/modp_numtoa.c

@@ -55,6 +55,7 @@ static void sn_strip_trailing_zeros(char* str)
 	if ( ! frac )
 		return;
 
+	char* start_dec = frac;
 	char* exp = 0;
 	char* trailing_zeros = 0;
 
@@ -80,6 +81,9 @@ static void sn_strip_trailing_zeros(char* str)
 		++frac;
 		}
 
+	if ( trailing_zeros == start_dec )
+		--trailing_zeros;
+
 	if ( trailing_zeros && exp )
 		{
 		for ( ; ; )

testing/btest/Baseline/language.double/out

@@ -44,12 +44,12 @@ max double value = 1.7976931348623157e+308 (PASS)
 0.5
 5.0
 
-1.e-13
+1e-13
 9.9999999999999998e-13
 9.9999999999999994e-12
-1.e-10
+1e-10
 1.0000000000000001e-09
-1.e-08
+1e-08
 9.9999999999999995e-08
 
 0.000001