update libpng

update libpng, the repo now requires a vcpkg setup for integrating but skipping the install step should allow it to work for windows an linux, mac might need more

Engine/lib/lpng/powerpc/.editorconfig

@@ -0,0 +1,8 @@
+# https://editorconfig.org
+
+root = false
+
+# FIXME
+[*.[ch]]
+max_doc_length = unset
+max_line_length = unset

Engine/lib/lpng/powerpc/filter_vsx_intrinsics.c

@@ -23,7 +23,7 @@
 #if PNG_POWERPC_VSX_OPT > 0
 
 #ifndef __VSX__
-#  error "This code requires VSX support (POWER7 and later). Please provide -mvsx compiler flag."
+#  error This code requires VSX support (POWER7 and later); please compile with -mvsx
 #endif
 
 #define vec_ld_unaligned(vec,data) vec = vec_vsx_ld(0,data)

Engine/lib/lpng/powerpc/powerpc_init.c

@@ -1,4 +1,3 @@
-
 /* powerpc_init.c - POWERPC optimised filter functions
  *
  * Copyright (c) 2018 Cosmin Truta
@@ -47,7 +46,7 @@ static int png_have_vsx(png_structp png_ptr);
 #include PNG_POWERPC_VSX_FILE
 
 #else  /* PNG_POWERPC_VSX_FILE */
-#  error "PNG_POWERPC_VSX_FILE undefined: no support for run-time POWERPC VSX checks"
+#  error PNG_POWERPC_VSX_FILE undefined: no support for run-time POWERPC VSX checks
 #endif /* PNG_POWERPC_VSX_FILE */
 #endif /* PNG_POWERPC_VSX_CHECK_SUPPORTED */