patch zlib for proper .pc file creation

patch/zlib.patch

@@ -0,0 +1,25 @@
+--- a/configure
++++ b/configure
+@@ -906,7 +906,6 @@
+ /^ARFLAGS *=/s#=.*#=$ARFLAGS#
+ /^RANLIB *=/s#=.*#=$RANLIB#
+ /^EXE *=/s#=.*#=$EXE#
+-/^prefix *=/s#=.*#=$prefix#
+ /^exec_prefix *=/s#=.*#=$exec_prefix#
+ /^libdir *=/s#=.*#=$libdir#
+ /^sharedlibdir *=/s#=.*#=$sharedlibdir#
+--- a/zlib.pc.in
++++ b/zlib.pc.in
+@@ -1,4 +1,4 @@
+-prefix=@prefix@
++prefix=
+ exec_prefix=@exec_prefix@
+ libdir=@libdir@
+ sharedlibdir=@sharedlibdir@
+@@ -9,5 +9,5 @@
+ Version: @VERSION@
+ 
+ Requires:
+-Libs: -L${libdir} -L${sharedlibdir} -lz
++Libs: ${libdir}/libz.a
+ Cflags: -I${includedir}