[mathmap] fix applying libpng15 patch

[Nils Philippsen]

commit 78b4ef7b4e82d51f6bb8b66a2f3198ff9ab5eaf5
Author: Nils Philippsen <nils at redhat.com>
Date:   Sat Dec 17 17:58:52 2011 +0100

    fix applying libpng15 patch

 mathmap.spec |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/mathmap.spec b/mathmap.spec
index 6cda37f..f347b38 100644
--- a/mathmap.spec
+++ b/mathmap.spec
@@ -46,7 +46,7 @@ generate pixels completely independent of the source.
 %setup -q
 %patch0 -p0 -b .system-libnoise
 %patch1 -p1 -b .vanilla-libnoise
-%patch2 -p2 -b .libpng15
+%patch2 -p1 -b .libpng15
 
 %build
 make %{?_smp_mflags}