gcc: disable dynamicbase for compiler binaries.

GCC's precompiled header mechanism is not compatible with ASLR, so GCC
itself needs dynamicbase to be disabled, but the runtime libraries would
still benefit from having it set, so only disable dynamicbase for GCC
itself.

mingw-w64-gcc/PKGBUILD

@@ -186,6 +186,9 @@ build() {
     _languages+=",objc,obj-c++"
   fi
 
+  local _LDFLAGS_FOR_TARGET="$LDFLAGS"
+  LDFLAGS+=" -Wl,--disable-dynamicbase"
+
   ../${_sourcedir}/configure \
     --prefix=${MINGW_PREFIX} \
     --with-local-prefix=${MINGW_PREFIX}/local \
@@ -225,7 +228,7 @@ build() {
     --with-bugurl="https://github.com/msys2/MINGW-packages/issues" \
     --with-gnu-as --with-gnu-ld \
     --with-boot-ldflags="${LDFLAGS} -static-libstdc++ -static-libgcc" \
-    LDFLAGS_FOR_TARGET="${LDFLAGS}" \
+    LDFLAGS_FOR_TARGET="${_LDFLAGS_FOR_TARGET}" \
     ${_conf}
 
   # While we're debugging -fopenmp problems at least.