build: enable -Wlogical-op for GCC 4.4+

Closes #1941

acinclude.m4

@@ -478,6 +478,11 @@ AC_DEFUN([CURL_CC_DEBUG_OPTS],
             tmp_CFLAGS="$tmp_CFLAGS -ftree-vrp"
           fi
 
+          dnl Only gcc 4.4 or later
+          if test "$compiler_num" -ge "404"; then
+            CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [logical-op])
+          fi
+
           dnl Only gcc 4.5 or later
           if test "$compiler_num" -ge "405"; then
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [jump-misses-init])

cmake/PickyWarnings.cmake

@@ -179,6 +179,7 @@ if(PICKY_COMPILER)
         list(APPEND _picky_enable
           -Wdouble-promotion               # clang  3.6  gcc  4.6  appleclang  6.1
           -Wformat=2                       # clang  3.0  gcc  4.8
+          -Wlogical-op                     #             gcc  4.4
           -Wtrampolines                    #             gcc  4.6
         )
       endif()