configure.ac/CMake: Check for round() and stdbool.h

Not all the compilers that HarfBuzz is buildable on supports round() and
has the header stdbool.h, so we check for them and define HAVE_ROUND and
HAVE_STDBOOL_H repsectively in our CFLAGS so that we include them only
when they are found, or use fallback implementations when necessary.

Also include FindPythonInterp earlier as we need PYTHON_EXECUTABLE to be
set for running the tests.

CMakeLists.txt

@@ -90,6 +90,8 @@ include_directories(AFTER
 add_definitions(-DHAVE_OT)
 add_definitions(-DHAVE_FALLBACK)
 
+# We need PYTHON_EXECUTABLE to be set for running the tests...
+include (FindPythonInterp)
 
 ## Functions and headers
 include (CheckFunctionExists)
@@ -103,7 +105,10 @@ macro (check_funcs) # Similar to AC_CHECK_FUNCS of autotools
     endif ()
   endforeach ()
 endmacro ()
-check_funcs(atexit mprotect sysconf getpagesize mmap isatty newlocale strtod_l)
+if (UNIX)
+  list(APPEND CMAKE_REQUIRED_LIBRARIES m)
+endif ()
+check_funcs(atexit mprotect sysconf getpagesize mmap isatty newlocale strtod_l round)
 check_include_file(unistd.h HAVE_UNISTD_H)
 if (${HAVE_UNISTD_H})
   add_definitions(-DHAVE_UNISTD_H)
@@ -116,6 +121,10 @@ check_include_file(xlocale.h HAVE_XLOCALE_H)
 if (${HAVE_XLOCALE_H})
   add_definitions(-DHAVE_XLOCALE_H)
 endif ()
+check_include_file(stdbool.h HAVE_STDBOOL_H)
+if (${HAVE_STDBOOL_H})
+  add_definitions(-DHAVE_STDBOOL_H)
+endif ()
 
 
 if (MSVC)
@@ -385,7 +394,6 @@ if (WIN32 AND HB_HAVE_DIRECTWRITE)
 endif ()
 
 if (HB_HAVE_GOBJECT)
-  include (FindPythonInterp)
   include (FindPerl)
 
   # Use the hints from glib-2.0.pc to find glib-mkenums

configure.ac

@@ -78,8 +78,15 @@ GTK_DOC_CHECK([1.15],[--flavour no-tmpl])
 ])
 
 # Functions, and headers
+
 AC_CHECK_FUNCS(atexit mprotect sysconf getpagesize mmap isatty newlocale strtod_l setlinebuf)
-AC_CHECK_HEADERS(unistd.h sys/mman.h xlocale.h)
+
+save_libs="$LIBS"
+LIBS="$LIBS -lm"
+AC_CHECK_FUNCS([round], ,[AC_CHECK_DECLS([round], , ,[#include <math.h>])])
+LIBS="$save_libs"
+
+AC_CHECK_HEADERS(unistd.h sys/mman.h xlocale.h stdbool.h)
 
 # Compiler flags
 AC_CANONICAL_HOST