Add patches to fix s390x build issues.

94212fa2a92b5d01be5da8235f02423249dd7b2a.patch

@@ -0,0 +1,25 @@
+From 94212fa2a92b5d01be5da8235f02423249dd7b2a Mon Sep 17 00:00:00 2001
+From: bubnikv <bubnikv@gmail.com>
+Date: Thu, 19 Sep 2019 08:56:47 +0200
+Subject: [PATCH] Another fix of admesh on big endian architectures, fixes
+ #2879
+
+---
+ src/admesh/stl_io.cpp | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/admesh/stl_io.cpp b/src/admesh/stl_io.cpp
+index af9bb4f98..ddf377c78 100644
+--- a/src/admesh/stl_io.cpp
++++ b/src/admesh/stl_io.cpp
+@@ -151,8 +151,8 @@ bool stl_write_binary(stl_file *stl, const char *file, const char *label)
+ 	memcpy(buffer, &stl->stats.number_of_facets, 4);
+ 	stl_internal_reverse_quads(buffer, 4);
+ 	fwrite(buffer, 4, 1, fp);
+-	for (size_t i = 0; i < stl->stats.number_of_facets; ++ i) {
+-		memcpy(buffer, stl->facet_start + i, 50);
++	for (const stl_facet &facet : stl->facet_start) {
++		memcpy(buffer, &facet, 50);
+ 		// Convert to little endian.
+ 		stl_internal_reverse_quads(buffer, 48);
+ 		fwrite(buffer, SIZEOF_STL_FACET, 1, fp);

patch-endianness

@@ -0,0 +1,26 @@
+diff --git a/src/admesh/stlinit.cpp b/src/admesh/stlinit.cpp
+index 693aad0..390fe56 100644
+--- a/src/admesh/stlinit.cpp
++++ b/src/admesh/stlinit.cpp
+@@ -36,6 +36,10 @@
+ #error "SEEK_SET not defined"
+ #endif
+ 
++#ifndef BOOST_LITTLE_ENDIAN
++extern void stl_internal_reverse_quads(char *buf, size_t cnt);
++#endif /* BOOST_LITTLE_ENDIAN */
++
+ static FILE* stl_open_count_facets(stl_file *stl, const char *file) 
+ {
+   	// Open the file in binary mode first.
+@@ -238,10 +242,6 @@ bool stl_open(stl_file *stl, const char *file)
+   	return result;
+ }
+ 
+-#ifndef BOOST_LITTLE_ENDIAN
+-extern void stl_internal_reverse_quads(char *buf, size_t cnt);
+-#endif /* BOOST_LITTLE_ENDIAN */
+-
+ void stl_allocate(stl_file *stl) 
+ {
+   	//  Allocate memory for the entire .STL file.

prusa-slicer.spec

@@ -3,7 +3,7 @@
 
 Name:           prusa-slicer
 Version:        2.1.0
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        3D printing slicer optimized for Prusa printers
 
 # The main PrusaSlicer code and resources are AGPLv3, with small parts as
@@ -20,9 +20,14 @@ Source0:        https://github.com/prusa3d/PrusaSlicer/archive/version_%version.
 Source1:        %name.desktop
 Source2:        %name.appdata.xml
 
-# The source fails to build on s390x, so disable it temporarily; see
+# Fix building on s390x
 # https://github.com/prusa3d/PrusaSlicer/issues/2879
-ExcludeArch: s390x
+Patch0:         https://github.com/prusa3d/PrusaSlicer/commit/94212fa2a92b5d01be5da8235f02423249dd7b2a.patch
+
+# Try to fix more endian-related compilation errors
+# https://github.com/prusa3d/PrusaSlicer/issues/2879
+# https://github.com/prusa3d/PrusaSlicer/pull/2981
+Patch1:         patch-endianness
 
 # Highly-parallel uild can run out of memory on PPC64le
 %ifarch ppc64le
@@ -395,6 +400,9 @@ make test ARGS=-V
 
 
 %changelog
+* Mon Sep 23 2019 Jason L Tibbitts III <tibbs@math.uh.edu> - 2.1.0-2
+- Fix the s390x build and re-enable it.
+
 * Fri Sep 13 2019 Jason L Tibbitts III <tibbs@math.uh.edu> - 2.1.0-1
 - Update to 2.1.0.