Simplify build system architecture optimization

This change to the build system rips out any usage of PROC along with
architecture-specific optimizations in favor of using -march=native where it is
supported.  This fixes broken builds on 64bit Intel systems and results in
better optimized code on systems running GCC 4.2+.

Review: https://reviewboard.asterisk.org/r/1852/
(closes issue ASTERISK-19462)
........

Merged revisions 361955 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 361956 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@361968 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configure.ac

@@ -1009,15 +1009,20 @@ else
 fi
 AC_SUBST(AST_SHADOW_WARNINGS)
 
-AC_MSG_CHECKING(for -march=native)
+AC_MSG_CHECKING(for -march=native support)
 if $(${CC} -march=native -S -o /dev/null -xc /dev/null > /dev/null 2>&1); then
-	AC_MSG_RESULT(yes)
-	AST_MARCH_NATIVE="-march=native"
+	if test "${CONFIG_CFLAGS}" = ""; then
+		AC_MSG_RESULT(yes)
+		AST_NATIVE_ARCH=1
+	else
+		AC_MSG_RESULT(user CFLAGS present)
+		AST_NATIVE_ARCH=
+	fi
 else
 	AC_MSG_RESULT(no)
-	AST_MARCH_NATIVE=
+	AST_NATIVE_ARCH=
 fi
-AC_SUBST(AST_MARCH_NATIVE)
+AC_SUBST(AST_NATIVE_ARCH)
 
 AC_MSG_CHECKING(for sysinfo)
 AC_LINK_IFELSE(