[introspection] Disable constructors for now

Since our types are not associated with their methods, marking
constructors makes them inaccessible from bindings.  Undo for now.

src/hb-blob.cc

diff --git a/src/hb-blob.cc b/src/hb-blob.cc
index 5c53016..5f58429 100644
--- a/src/hb-blob.cc
+++ b/src/hb-blob.cc
@@ -77,7 +77,7 @@
 }
 
 /**
- * hb_blob_create: (constructor)
+ * hb_blob_create: (Xconstructor)
  * @data: (array length=length): Pointer to blob data.
  * @length: Length of @data in bytes.
  * @mode: Memory mode for @data.

src/hb-buffer.cc

diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 8143a1e..54626db 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -604,7 +604,7 @@
 /* Public API */
 
 /**
- * hb_buffer_create: (constructor)
+ * hb_buffer_create: (Xconstructor)
  *
  * 
  *

src/hb-face.cc

diff --git a/src/hb-face.cc b/src/hb-face.cc
index 10f4302..2713226 100644
--- a/src/hb-face.cc
+++ b/src/hb-face.cc
@@ -150,7 +150,7 @@
 }
 
 /**
- * hb_face_create: (constructor)
+ * hb_face_create: (Xconstructor)
  * @blob: 
  * @index: 
  *

src/hb-font.cc

diff --git a/src/hb-font.cc b/src/hb-font.cc
index f02afa2..42e0cee 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -231,7 +231,7 @@
 
 
 /**
- * hb_font_funcs_create: (constructor)
+ * hb_font_funcs_create: (Xconstructor)
  *
  * 
  *
@@ -839,7 +839,7 @@
  */
 
 /**
- * hb_font_create: (constructor)
+ * hb_font_create: (Xconstructor)
  * @face: a face.
  *
  * 

src/hb-set.cc

diff --git a/src/hb-set.cc b/src/hb-set.cc
index 161924e..59a0af4 100644
--- a/src/hb-set.cc
+++ b/src/hb-set.cc
@@ -31,7 +31,7 @@
 
 
 /**
- * hb_set_create: (constructor)
+ * hb_set_create: (Xconstructor)
  *
  * Return value: (transfer full):
  *

src/hb-shape-plan.cc

diff --git a/src/hb-shape-plan.cc b/src/hb-shape-plan.cc
index 4e734d7..b44a9e2 100644
--- a/src/hb-shape-plan.cc
+++ b/src/hb-shape-plan.cc
@@ -84,7 +84,7 @@
  */
 
 /**
- * hb_shape_plan_create: (constructor)
+ * hb_shape_plan_create: (Xconstructor)
  * @face: 
  * @props: 
  * @user_features: (array length=num_user_features):

src/hb-unicode.cc

diff --git a/src/hb-unicode.cc b/src/hb-unicode.cc
index 807d5c1..5b44913 100644
--- a/src/hb-unicode.cc
+++ b/src/hb-unicode.cc
@@ -151,7 +151,7 @@
 #endif
 
 /**
- * hb_unicode_funcs_create: (constructor)
+ * hb_unicode_funcs_create: (Xconstructor)
  * @parent: (allow-none):
  *
  *