* Add fix for overflow in kind=light mgl_example

mathgl-2.4.1-fix_overflow.patch

@@ -0,0 +1,12 @@
+diff -r b759fc50f42e src/pixel.cpp
+--- a/src/pixel.cpp	Fri Feb 16 00:41:32 2018 +0000
++++ b/src/pixel.cpp	Fri Feb 16 00:42:35 2018 +0000
+@@ -274,7 +274,7 @@
+ //	if(!r)	return r;	// NOTE r must be provided!
+ 	if(p.a<=0)	{	memset(r,0,4);	return r;	}
+ 	float b0=0,b1=0,b2=0, ar,ag,ab,dif;
+-	const size_t nl = p.sub>=0?p.sub:1-p.sub;
++	const size_t nl = p.sub>=0?p.sub:-1-p.sub;
+ 	const bool glob = !get(MGL_LOCAL_LIGHT);
+ 	ar = ag = ab = glob?AmbBr:Sub[nl].AmbBr;
+ 	dif = glob?DifBr:Sub[nl].DifBr;

mathgl.spec

@@ -19,7 +19,7 @@
 
 Name:          mathgl
 Version:       2.4.1
-Release:       3%{?dist}
+Release:       4%{?dist}
 Summary:       Cross-platform library for making high-quality scientific graphics
 Summary(de):   Plattformübergreifende Bibliothek für hochwertige wissenschaftliche Graphiken
 Summary(ru):   Библиотека для осуществления высококачественной визуализации данных
@@ -52,6 +52,9 @@ Patch6:        mathgl-2.4.1-gcc7.patch
 # Disable uppdate-{destop,mine}-database during install process
 Patch7:        mathgl-2.4.1-no_updatedb.patch
 
+# Fix overflow (mathgl mailing list, 14/2/18. Fixed upstream
+Patch8:        mathgl-2.4.1-fix_overflow.patch
+
 Requires:      %{name}-common = %{version}-%{release}
 
 # mandatory packages
@@ -365,6 +368,7 @@ done
 %patch5 -p1 -b .lang
 %patch6 -p1 -b .gcc7
 %patch7 -p1 -b .no_updatedb
+%patch8 -p1 -b .fix_overflow
 %if 0%{?with_octave}
 %patch3 -p1 -b .nooctaveinstall
 %else
@@ -681,6 +685,9 @@ fi
 %endif
 
 %changelog
+* Fri Feb 16 2018 D Haley <mycae gmx com> - 2.4.1-4
+- Fix overflow in mgl_example (light)
+
 * Tue Feb 13 2018 Sandro Mani <manisandro@gmail.com> - 2.4.1-3
 - Rebuild (giflib)