Don't disable target optimizations when cross-compiling. (cloudflare#15)

* PS-237 Don't disable target optimizations when cross-compiling.

AFAICT there's no reason to check the host platform here. The test only runs the compiler; it doesn't execute the output.

* Add misc intermediate files to .gitignore.

.gitignore

@@ -23,3 +23,7 @@
 /zlib.pc
 
 .DS_Store
+
+/build
+/Makefile
+/configure.log

configure

@@ -743,7 +743,7 @@ EOF
 fi
 
 # Check for AMD64 hardware support.
-if [ x$TGT_ARCH = "xx86_64" -a $(uname -m) = "x86_64" -o x$TGT_ARCH = "xamd64" -a $(uname -m) = "amd64" ] ; then
+if [ x$TGT_ARCH = "xx86_64" -o x$TGT_ARCH = "xamd64" ] ; then
 
   # Check for SSE4.2 and CRC support
 cat > $test.c << EOF
@@ -779,7 +779,7 @@ EOF
     echo "Checking for PCLMUL support ... No" | tee -a configure.log
   fi
 
-elif [ x$TGT_ARCH = "xaarch64" -a $(uname -m) = "aarch64" ] ; then
+elif [ x$TGT_ARCH = "xaarch64" ] ; then
 
   # Check for NEON and CRC support
 cat > $test.c << EOF