[libpng16] Removed cc -E workround, corrected png_get_palette_max API Tested on SUN OS cc 5.9,

which demonstrates the tokenization problem previously avoided by using /lib/cpp.
Since all .dfn output is now protected in double quotes unless it is to be macro
substituted the fix should work everywhere.

configure.ac

@@ -53,8 +53,7 @@ AC_PROG_CC
 AM_PROG_AS
 LT_PATH_LD
 AC_PROG_CPP
-AC_CHECK_TOOL(SED, sed, :)
-AC_CHECK_TOOL(AWK, awk, :)
+AC_PROG_AWK
 AC_PROG_INSTALL
 AC_PROG_LN_S
 AC_PROG_MAKE_SET
@@ -64,30 +63,23 @@ dnl compatible later version may be used
 LT_INIT([win32-dll])
 LT_PREREQ([2.4.2])
 
-# On Solaris 10 and 12 CPP gets set to cc -E, however this still
-# does some input parsing.  We need strict ANSI-C style tokenization,
-# check this:
-AC_REQUIRE_CPP
-AC_MSG_CHECKING([for a C preprocessor that does not parse its input])
-AC_PREPROC_IFELSE([AC_LANG_SOURCE([[1.1.1 16BIT]])],
-   [DFNCPP="$CPP"],
-   [  DFNCPP=""
-      sav_CPP="$CPP"
-      for CPP in "${CC-cc} -E" "${CC-cc} -E -traditional-cpp" "/lib/cpp" "cpp"
-      do
-         AC_PREPROC_IFELSE([AC_LANG_SOURCE([[1.1.1 16BIT]])],
-            [DFNCPP="$CPP"]
-            [break],,)
-      done
-      CPP="$sav_CPP"
-   ])
-if test -n "$DFNCPP"; then
-   AC_MSG_RESULT([$DFNCPP])
-   AC_SUBST(DFNCPP)
+# Some awks crash when confronted with pnglibconf.dfa, do a test run now
+# to make sure this doesn't happen
+AC_MSG_CHECKING([that AWK works])
+if ${AWK} -f ${srcdir}/scripts/options.awk out="/dev/null" version=search\
+   ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
+   ${srcdir}/pngusr.dfa 1>&2
+then
+   AC_MSG_RESULT([ok])
 else
-   AC_MSG_FAILURE([not found], 1)
+   AC_MSG_FAILURE([failed], 1)
 fi
 
+# This is a remnant of the old cc -E validation, where it may have been
+# necessary to use a different preprocessor for .dfn files
+DFNCPP="$CPP"
+AC_SUBST(DFNCPP)
+
 # -Werror cannot be passed to GCC in CFLAGS because configure will fail (it
 # checks the compiler with a program that generates a warning), add the
 # following option to deal with this
@@ -115,7 +107,6 @@ AC_ARG_ENABLE(werror,
 
 # Checks for header files.
 AC_HEADER_STDC
-AC_CHECK_HEADERS([malloc.h stdlib.h string.h strings.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST