[libpng16] Use pnglibconf.h.prebuilt when building for ANDROID with cmake

Github issue 162, by rcdaily).

ANNOUNCE

-Libpng 1.6.33beta03 - September 3, 2017
+Libpng 1.6.33beta03 - September 8, 2017
 
 This is not intended to be a public release. It will be replaced
 within a few weeks by a public version or by another test version.
@@ -39,10 +39,12 @@ Version 1.6.33beta02 [September 3, 2017]
     changed date of contrib/oss-fuzz files.
   Enabled ARM support in CMakeLists.txt (Bernd Kuhls).
 
-Version 1.6.33beta03 [September 3, 2017]
+Version 1.6.33beta03 [September 8, 2017]
   Fixed incorrect typecast of some arguments to png_malloc() and
     png_calloc() that were png_uint_32 instead of png_alloc_size_t
     (Bug report by "irwir" in Github libpng issue #175).
+  Use pnglibconf.h.prebuilt when building for ANDROID with cmake (Github
+    issue 162, by rcdaily).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -6009,10 +6009,12 @@ Version 1.6.33beta02 [September 3, 2017]
     changed date of contrib/oss-fuzz files.
   Enabled ARM support in CMakeLists.txt (Bernd Kuhls).
 
-Version 1.6.33beta03 [September 3, 2017]
+Version 1.6.33beta03 [September 8, 2017]
   Fixed incorrect typecast of some arguments to png_malloc() and
     png_calloc() that were png_uint_32 instead of png_alloc_size_t
     (Bug report by "irwir" in Github libpng issue #175).
+  Use pnglibconf.h.prebuilt when building for ANDROID with cmake (Github
+    issue 162, by rcdaily).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CMakeLists.txt

@@ -262,7 +262,7 @@ find_program(AWK NAMES gawk awk)
 
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
 
-if(NOT AWK)
+if(NOT AWK OR ANDROID)
   # No awk available to generate sources; use pre-built pnglibconf.h
   configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
                  ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)