testing/netcdf: fix build in s390x

Use a patch from debian: 18d5a1d35b

testing/netcdf/APKBUILD

@@ -21,7 +21,9 @@ subpackages="
 	$pkgname-dev
 	$pkgname-utils:utils
 	"
-source="$pkgname-$pkgver.tar.gz::https://github.com/Unidata/netcdf-c/archive/v$pkgver.tar.gz"
+source="$pkgname-$pkgver.tar.gz::https://github.com/Unidata/netcdf-c/archive/v$pkgver.tar.gz
+	byteswap.patch
+	"
 builddir="$srcdir/$pkgname-c-$pkgver"
 
 build() {
@@ -57,4 +59,5 @@ check() {
 	# One test failure in nc_test as reported in https://github.com/Unidata/netcdf-c/issues/808
 	ctest -E nc_test
 }
-sha512sums="15922818fdd71be285eb7dd2fc9be2594fe9af979de3ed316465636c7bbdaec65eb151ca57ef8b703e6a360cdba036b8f9bc193ddff01ff7ce4214c0a66efa79  netcdf-4.7.4.tar.gz"
+sha512sums="15922818fdd71be285eb7dd2fc9be2594fe9af979de3ed316465636c7bbdaec65eb151ca57ef8b703e6a360cdba036b8f9bc193ddff01ff7ce4214c0a66efa79  netcdf-4.7.4.tar.gz
+fa74a75eb064901878dc37b2049534bec7571885393f78692d7ac27ad9a1ec622574bf4bbfdb741d714c45b4a0b8a1ebbd532277603c154d50513eecad70d002  byteswap.patch"

testing/netcdf/byteswap.patch

@@ -0,0 +1,18 @@
+Description: Add forward declarations for byteswap8 & byteswap4.
+Author: Dennis Heimbigner
+Bug: https://github.com/Unidata/netcdf-c/issues/1687
+
+diff --git a/libdispatch/dfilter.c b/libdispatch/dfilter.c
+index 8938464..8efe591 100644
+--- a/libdispatch/dfilter.c
++++ b/libdispatch/dfilter.c
+@@ -20,6 +20,9 @@
+ #include "hdf5internal.h"
+ #endif
+ 
++static void byteswap8(unsigned char*);
++static void byteswap4(unsigned char*);
++
+ /*
+ Unified filter related code
+ */