fix abs family for -0 value

srcs/ft_abs.c

@@ -1,8 +1,12 @@
 #include "libft.h"
 
+/**
+ * returns the absolute value of an int number
+ */
+
 int ft_abs(int n)
 {
-	if (n < 0)
-		n *= -1;
+	if (n <= 0)
+		n *= -1; // also works for -0
 	return (n);
 }

srcs/ft_fabs.c

@@ -1,8 +1,12 @@
 #include "libft.h"
 
+/**
+ * returns the absolute value of a double number
+ */
+
 double ft_fabs(double n)
 {
-	if (n < 0)
-		n *= -1;
+	if (n <= 0)
+		n *= -1; // also works for -0
 	return (n);
 }

srcs/ft_labs.c

@@ -1,8 +1,12 @@
 #include "libft.h"
 
+/**
+ * returns the absolute value of a long int number
+ */
+
 long int ft_labs(long int n)
 {
-	if (n < 0)
-		n *= -1;
+	if (n <= 0)
+		n *= -1; // also works for -0
 	return (n);
 }