[config] Replace HAVE_FALLBACK with HB_NO_FALLBACK_SHAPE

This disables fallback shaper in tiny builds.  Projects that don't
use our build system and want to disable fallback shaper (eg. Firefox)
should define HB_NO_FALLBACK_SHAPE now.

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

CMakeLists.txt

@@ -88,8 +88,6 @@ include_directories(AFTER
   ${PROJECT_BINARY_DIR}/src
 )
 
-add_definitions(-DHAVE_FALLBACK)
-
 # We need PYTHON_EXECUTABLE to be set for running the tests...
 include (FindPythonInterp)
 

configure.ac

@@ -136,14 +136,6 @@ AM_CONDITIONAL(HAVE_PTHREAD, $have_pthread)
 
 dnl ==========================================================================
 
-have_fallback=true
-if $have_fallback; then
-	AC_DEFINE(HAVE_FALLBACK, 1, [Have simple TrueType Layout backend])
-fi
-AM_CONDITIONAL(HAVE_FALLBACK, $have_fallback)
-
-dnl ===========================================================================
-
 AC_ARG_WITH(glib,
 	[AS_HELP_STRING([--with-glib=@<:@yes/no/auto@:>@],
 			[Use glib @<:@default=auto@:>@])],,

src/Makefile.am

@@ -28,10 +28,6 @@ HBSOURCES =  $(HB_BASE_sources)
 HBSOURCES += $(HB_BASE_RAGEL_GENERATED_sources)
 HBHEADERS = $(HB_BASE_headers)
 
-if HAVE_FALLBACK
-HBSOURCES += $(HB_FALLBACK_sources)
-endif
-
 if HAVE_PTHREAD
 HBCFLAGS += $(PTHREAD_CFLAGS)
 HBNONPCLIBS += $(PTHREAD_LIBS)

src/Makefile.sources

@@ -36,6 +36,7 @@ HB_BASE_sources = \
 	hb-dispatch.hh \
 	hb-face.cc \
 	hb-face.hh \
+	hb-fallback-shape.cc \
 	hb-font.cc \
 	hb-font.hh \
 	hb-iter.hh \
@@ -200,10 +201,6 @@ HB_BASE_headers = \
 	hb.h \
 	$(NULL)
 
-HB_FALLBACK_sources = \
-	hb-fallback-shape.cc	\
-	$(NULL)
-
 # Optional Sources and Headers with external deps
 
 HB_FT_sources = hb-ft.cc

src/hb-config.hh

@@ -99,6 +99,7 @@
 #endif
 
 #ifdef HB_NO_LEGACY
+#define HB_NO_FALLBACK_SHAPE
 #define HB_NO_OT_LAYOUT_BLACKLIST
 #define HB_NO_OT_SHAPE_FALLBACK
 #endif

src/hb-fallback-shape.cc

@@ -26,6 +26,7 @@
 
 #include "hb-shaper-impl.hh"
 
+#ifndef HB_NO_FALLBACK_SHAPE
 
 /*
  * shaper face data
@@ -120,3 +121,5 @@ _hb_fallback_shape (hb_shape_plan_t    *shape_plan HB_UNUSED,
 
   return true;
 }
+
+#endif

src/hb-shaper-list.hh

@@ -47,6 +47,6 @@ HB_SHAPER_IMPLEMENT (directwrite)
 HB_SHAPER_IMPLEMENT (coretext)
 #endif
 
-#ifdef HAVE_FALLBACK
+#ifndef HB_NO_FALLBACK_SHAPE
 HB_SHAPER_IMPLEMENT (fallback) /* <--- This should be last. */
 #endif