chore(build): improve hardening flags

Using "-fstack-protector-all" makes "--param ssp-buffer-size=1" pointless.

For ASLR "-pie -fPIE" is needed instead of just "-fPIE".

qtox.pro

@@ -47,16 +47,17 @@ CONFIG   += silent
 # Hardening flags (ASLR, warnings, etc)
 # TODO: add `-Werror` to hardening flags once all warnings are fixed
 win32 {
-    QMAKE_CXXFLAGS += -fPIE \
+    QMAKE_CXXFLAGS += -pie \
+                      -fPIE \
                       -Wstrict-overflow \
                       -Wstrict-aliasing
 } else {
     QMAKE_CXXFLAGS += -fstack-protector-all \
+                      -pie \
                       -fPIE \
                       -Wstack-protector \
                       -Wstrict-overflow \
-                      -Wstrict-aliasing \
-                      --param ssp-buffer-size=1
+                      -Wstrict-aliasing
 }
 
 # osx & windows cannot into security (build on it fails with those enabled)