Merge branch '8.6'

ChangeLog

@@ -31,6 +31,7 @@
 - strict round down on jpeg shrink on load [davidwood]
 - configure test for g++ 7.2 and composite.cpp
 - don't Ping in magickload, too unreliable
+- ensure WebP can add metadata when compiled with libwebpmux [lovell]
 
 12/2/18 started 8.6.3
 - use pkg-config to find libjpeg, if we can

libvips/foreign/vips2webp.c

@@ -106,7 +106,7 @@ vips_webp_writer_init( VipsWebPWriter *writer )
 	writer->max_size = 0;
 }
 
-static int
+static gboolean
 vips_webp_writer_append( VipsWebPWriter *writer, 
 	const uint8_t *data, guint64 data_size )
 {
@@ -155,7 +155,7 @@ vips_webp_writer_append( VipsWebPWriter *writer,
  * lots of our tests start failing.
  */
 #ifdef HAVE_LIBWEBPMUX
-static int
+static gboolean
 vips_webp_writer_appendle( VipsWebPWriter *writer, uint32_t val, int n )
 {
 	unsigned char buf[4];
@@ -171,19 +171,19 @@ vips_webp_writer_appendle( VipsWebPWriter *writer, uint32_t val, int n )
 	return( vips_webp_writer_append( writer, buf, n ) ); 
 }
 
-static int
+static gboolean
 vips_webp_writer_appendle32( VipsWebPWriter *writer, uint32_t val )
 {
 	return( vips_webp_writer_appendle( writer, val, 4 ) ); 
 }
 
-static int
+static gboolean
 vips_webp_writer_appendle24( VipsWebPWriter *writer, uint32_t val )
 {
 	return( vips_webp_writer_appendle( writer, val, 3 ) ); 
 }
 
-static int
+static gboolean
 vips_webp_writer_appendcc( VipsWebPWriter *writer, const char buf[4] )
 {
 	return( vips_webp_writer_append( writer, (const uint8_t *) buf, 4 ) ); 
@@ -215,7 +215,7 @@ vips_webp_writer_unset( VipsWebPWriter *writer )
 	VIPS_FREE( writer->mem );
 }
 
-static int
+static gboolean
 memory_write( const uint8_t *data, size_t data_size,
 	const WebPPicture *picture ) 
 {