Imaging.h: confusion with system

The file `libImaging/Imaging.h` gets installed flat on
Ubuntus into the public Python includes.

When building a newer version of Pillow from source and
hinting the Python includes "too early" in includes, e.g.
in package managers, this can confuse the two files and
pick up the external file over the internal one. With
different versions, this mismatch can lead to build errors,
e.g. undefined macros.

The most robust way to avoid this is to pre-fix the internal
include accordingly, so that the relative path to the including
file has to match as well.

src/_imaging.c

@@ -88,7 +88,7 @@
 #endif
 #endif
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #define _USE_MATH_DEFINES
 #include <math.h>

src/_imagingcms.c

@@ -31,7 +31,7 @@ kevin@cazabon.com\n\
 #include "datetime.h"
 
 #include "lcms2.h"
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #define PYCMSVERSION "1.0.0 pil"
 

src/_imagingft.c

@@ -20,7 +20,7 @@
 
 #define PY_SSIZE_T_CLEAN
 #include "Python.h"
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #include <ft2build.h>
 #include FT_FREETYPE_H

src/_imagingmath.c

@@ -15,7 +15,7 @@
 
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #include "math.h"
 #include "float.h"

src/_imagingmorph.c

@@ -12,7 +12,7 @@
  */
 
 #include "Python.h"
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #define LUT_SIZE (1<<9)
 

src/_imagingtk.c

@@ -14,7 +14,7 @@
 
 
 #include "Python.h"
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #include "_tkmini.h"
 

src/_webp.c

@@ -1,6 +1,6 @@
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 #include <webp/encode.h>
 #include <webp/decode.h>
 #include <webp/types.h>

src/decode.c

@@ -32,7 +32,7 @@
 #define PY_SSIZE_T_CLEAN
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #include "Gif.h"
 #include "Raw.h"

src/display.c

@@ -25,7 +25,7 @@
 
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 /* -------------------------------------------------------------------- */
 /* Windows DIB support */

src/encode.c

@@ -25,7 +25,7 @@
 #define PY_SSIZE_T_CLEAN
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 #include "Gif.h"
 
 #ifdef HAVE_UNISTD_H

src/map.c

@@ -20,7 +20,7 @@
 
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 /* compatibility wrappers (defined in _imaging.c) */
 extern int PyImaging_CheckBuffer(PyObject* buffer);

src/outline.c

@@ -19,7 +19,7 @@
 
 #include "Python.h"
 
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 
 /* -------------------------------------------------------------------- */

src/path.c

@@ -27,7 +27,7 @@
 
 
 #include "Python.h"
-#include "Imaging.h"
+#include "libImaging/Imaging.h"
 
 #include <math.h>