fix autofit loop on non-scaleable fonts

see https://github.com/libvips/libvips/issues/1178

ChangeLog

@@ -1,3 +1,6 @@
+21/11/18 started 8.7.3
+- fix infinite loop for autofit with non-scaleable font 
+
 21/11/18 started 8.7.2
 - more info output for temp files to help diagnose problems
 - vips_text() could set the wrong DPI

configure.ac

@@ -2,7 +2,7 @@
 
 # also update the version number in the m4 macros below
 
-AC_INIT([vips], [8.7.2], [vipsip@jiscmail.ac.uk])
+AC_INIT([vips], [8.7.3], [vipsip@jiscmail.ac.uk])
 # required for gobject-introspection
 AC_PREREQ(2.62)
 
@@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # user-visible library versioning
 m4_define([vips_major_version], [8])
 m4_define([vips_minor_version], [7])
-m4_define([vips_micro_version], [2])
+m4_define([vips_micro_version], [3])
 m4_define([vips_version],
           [vips_major_version.vips_minor_version.vips_micro_version])
 
@@ -38,7 +38,7 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date -u -r ChangeLog`
 #   binary interface changes not backwards compatible?: reset age to 0
 
 LIBRARY_CURRENT=51
-LIBRARY_REVISION=2
+LIBRARY_REVISION=3
 LIBRARY_AGE=9
 
 # patched into include/vips/version.h

libvips/create/text.c

@@ -265,6 +265,12 @@ vips_text_autofit( VipsText *text )
 		previous_dpi = text->dpi;
 
 		text->dpi = difference < 0 ? text->dpi * 2 : text->dpi / 2;
+
+		/* This can happen with some fonts that don't resize
+		 * gracefully.
+		 */
+		if( text->dpi < 2 )
+			break;
 	}
 
 	if( difference < 0 ) {