Update nanosvg library to latest upstream version

commit ccdb1995134d340a93fb20e3a3d323ccb3838dd0
Merge: 3cdd4a9 419782d
Author: Mikko Mononen <memononen@gmail.com>
Date:   Fri Sep 3 21:24:42 2021 +0300

    Merge pull request #198 from ctrlcctrlv/CVE_2019_1000032

    Fix decimal values in color fields (nsvg__parseColorRGB, nsvg__parseColorHex)

2 files changed, 31 insertions, 32 deletions

diff --git a/nanosvg/README.txt b/nanosvg/README.txt
index 7bea79582..ec3235e8b 100644
--- a/nanosvg/README.txt
+++ b/nanosvg/README.txt
@@ -22,38 +22,34 @@ For more information see README.bundled-libs.txt in FLTK's root directory.
 Changes in the FLTK fork, branch 'fltk':
 -----------------------------------------
 
-$ git show --no-patch fltk_2021-02-22
-tag fltk_2021-02-22
-Tagger: Albrecht Schlosser <...>
-Date:   Mon Feb 22 14:16:58 2021 +0100
+$ git show --no-patch fltk_2021-09-13
+tag fltk_2021-09-13
+Tagger: Albrecht Schlosser <albrechts.fltk@online.de>
+Date:   Mon Sep 13 19:09:40 2021 +0200
 
-Included in FLTK 1.4.x as of Feb 22, 2021
+FLTK modifications as of Sep 13, 2021:
 
-Latest upstream changes:
-------------------------
-
-commit 3e403ec72a9145cbbcc6c63d94a4caf079aafec2
-Merge: cc6c08d 45eb9f8
-Author: Mikko Mononen <...>
-Date:   Fri Nov 20 12:53:11 2020 +0200
-
-    Merge pull request #189 from fvogelnew1/Fix-for-#188
+$ git shortlog master..fltk
+AlbrechtS (2):
+      Fix Visual Studio compilation error (missing long long).
+      Modify rasterizer to support non-square X,Y axes scaling.
 
-    Update nanosvg.h
+Greg Ercolano (1):
+      Clip integer RGB percent values > 100
 
-Changes in branch 'fltk':
+Latest upstream commit (master):
 
-  $ git shortlog master..fltk
+commit ccdb1995134d340a93fb20e3a3d323ccb3838dd0
+Merge: 3cdd4a9 419782d
+Author: Mikko Mononen <memononen@gmail.com>
+Date:   Fri Sep 3 21:24:42 2021 +0300
 
-    AlbrechtS (2):
-      Fix Visual Studio compilation error (missing long long).
-      Modify rasterizer to support non-square X,Y axes scaling.
+    Merge pull request #198 from ctrlcctrlv/CVE_2019_1000032
 
-    Greg Ercolano (1):
-      Address crash defined in fltk's issue 180
+    Fix decimal values in color fields (nsvg__parseColorRGB, nsvg__parseColorHex)
 
-commit a1eea27b3db2d15d924ea823dd0acc5bd2aa56f1
-Author: Greg Ercolano <...>
+commit 461ad7de70d5fd3f09fc214e4baaadb830a2a270 (HEAD -> fltk, tag: fltk_2021-09-13, origin/fltk, origin/HEAD)
+Author: Greg Ercolano <erco@seriss.com>
 Date:   Mon Jan 18 15:05:13 2021 -0800
 
-    Address crash defined in fltk's issue 180
+    Clip integer RGB percent values > 100
diff --git a/nanosvg/nanosvg.h b/nanosvg/nanosvg.h
index 035b0e52e..0175ade74 100644
--- a/nanosvg/nanosvg.h
+++ b/nanosvg/nanosvg.h
@@ -1223,25 +1223,23 @@ static const char* nsvg__getNextPathItem(const char* s, char* it)
 
 static unsigned int nsvg__parseColorHex(const char* str)
 {
-	// FLTK: Solve fltk issue#180 / CVE-2019-1000032
 	unsigned int r=0, g=0, b=0;
 	if (sscanf(str, "#%2x%2x%2x", &r, &g, &b) == 3 )		// 2 digit hex
 		return NSVG_RGB(r, g, b);
 	if (sscanf(str, "#%1x%1x%1x", &r, &g, &b) == 3 )		// 1 digit hex, e.g. #abc -> 0xccbbaa
-		return NSVG_RGB(r*17, g*17, b*17);			// has same effect as (r<<4|r), (g<<4|g), ..
+		return NSVG_RGB(r*17, g*17, b*17);			// same effect as (r<<4|r), (g<<4|g), ..
 	return NSVG_RGB(128, 128, 128);
 }
 
 static unsigned int nsvg__parseColorRGB(const char* str)
 {
-	// FLTK: Solve fltk issue#180 / CVE-2019-1000032
 	unsigned int r=0, g=0, b=0;
 	if (sscanf(str, "rgb(%u, %u, %u)", &r, &g, &b) == 3)		// decimal integers
 		return NSVG_RGB(r, g, b);
 	if (sscanf(str, "rgb(%u%%, %u%%, %u%%)", &r, &g, &b) == 3) {	// decimal integer percentage
-	        r = (r <= 100) ? ((r*255)/100) : 255;			// clip percentages >100
-	        g = (g <= 100) ? ((g*255)/100) : 255;
-	        b = (b <= 100) ? ((b*255)/100) : 255;
+		r = (r <= 100) ? ((r*255)/100) : 255;			// FLTK: clip percentages >100
+		g = (g <= 100) ? ((g*255)/100) : 255;
+		b = (b <= 100) ? ((b*255)/100) : 255;
 		return NSVG_RGB(r, g, b);
 	}
 	return NSVG_RGB(128, 128, 128);
@@ -2188,7 +2186,12 @@ static void nsvg__pathArcTo(NSVGparser* p, float* cpx, float* cpy, float* args,
 	// The loop assumes an iteration per end point (including start and end), this +1.
 	ndivs = (int)(fabsf(da) / (NSVG_PI*0.5f) + 1.0f);
 	hda = (da / (float)ndivs) / 2.0f;
-	kappa = fabsf(4.0f / 3.0f * (1.0f - cosf(hda)) / sinf(hda));
+	// Fix for ticket #179: division by 0: avoid cotangens around 0 (infinite)
+	if ((hda < 1e-3f) && (hda > -1e-3f))
+		hda *= 0.5f;
+	else
+		hda = (1.0f - cosf(hda)) / sinf(hda);
+	kappa = fabsf(4.0f / 3.0f * hda);
 	if (da < 0.0f)
 		kappa = -kappa;