improve QT check; refs #41

ax_check_qt.m4

@@ -48,6 +48,7 @@ AC_DEFUN([AX_CXX_QT_TOOL], [
 ])
 
 AC_DEFUN([AX_CXX_QT_TOOLS], [
+  AX_CXX_QT_TOOL(QMAKE, qmake)
   AX_CXX_QT_TOOL(MOC, moc)
   AX_CXX_QT_TOOL(UIC, uic)
   AX_CXX_QT_TOOL(RCC, rcc)
@@ -62,17 +63,25 @@ AC_DEFUN([AX_CXX_CHECK_QT], [
   PKG_CHECK_MODULES([$1], [${qt_modules//Qt/Qt5}], [
     HAVE_$1=1
     AC_DEFINE([HAVE_$1])
-    CPPFLAGS+=" ${$1_CFLAGS}"
+    AM_CPPFLAGS+=" ${$1_CFLAGS}"
-    CXXFLAGS+=" ${$1_CFLAGS}"
+    AM_CXXFLAGS+=" ${$1_CFLAGS}"
     LIBS+=" ${$1_LIBS}"
   ], [
     PKG_CHECK_MODULES([$1], [${qt_modules}], [
       HAVE_$1=1
       AC_DEFINE([HAVE_$1])
-      CPPFLAGS+=" ${$1_CFLAGS}"
+      AM_CPPFLAGS+=" ${$1_CFLAGS}"
-      CXXFLAGS+=" ${$1_CFLAGS}"
+      AM_CXXFLAGS+=" ${$1_CFLAGS}"
       LIBS+=" ${$1_LIBS}"
     ])
   ])
   AM_CONDITIONAL(HAVE_$1, test $HAVE_$1 -eq 1)
+  AC_SUBST(AM_CPPFLAGS)
+  AC_SUBST(AM_CXXFLAGS)
+  AX_CHECK_COMPILE_FLAG(-fPIC, [AM_CXXFLAGS+=" -fPIC"])
+  AX_CHECK_COMPILE_FLAG(-DPIC, [AM_CXXFLAGS+=" -DPIC"])
+  AX_CHECK_COMPILE_FLAG(-fPIE, [AM_CXXFLAGS+=" -fPIE"])
+  AX_CHECK_LINK_FLAG(-fPIC, [LDFLAGS+=" -fPIC"])
+  AX_CHECK_LINK_FLAG(-DPIC, [LDFLAGS+=" -DPIC"])
+  AX_CHECK_LINK_FLAG(-fPIE, [LDFLAGS+=" -fPIE"])
 ])