Changes

Use armv6 optimization for armhf to stay compatible with the new Raspberry Pi Raspbian distribution.

Change/Lower ARM Requierements for GNU/Linux & Android-GNU/Linux ARM: ARMv7hf -> ARMv6hf, ARMv7-soft -> ARMv5te/ARMV6 (soft)

 platform build config files:
   lib/gluegen-cpptasks-linux-armv7.xml   -> lib/gluegen-cpptasks-linux-armv6.xml
   lib/gluegen-cpptasks-linux-armv7hf.xml -> lib/gluegen-cpptasks-linux-armv6hf.xml

 properties:
   isLinuxARMv7             -> isLinuxARMv6
   isLinuxARMv7Armel        -> isLinuxARMv6Armel
   isLinuxARMv7Armhf        -> isLinuxARMv6Armhf
   isAndroidARMv7           -> isAndroidARMv6
   isAndroidARMv7Armel      -> isAndroidARMv6Armel
   isAndroidARMv7Armhf      -> isAndroidARMv6Armhf

 targets:
   compiler.cfg.linux.armv7 -> compiler.cfg.linux.armv6
   linker.cfg.linux.armv7   -> linker.cfg.linux.armv6

 compiler.cfg.linux.armv6:
      <compilerarg value="-fpic" />
      <compilerarg value="-march=armv5te" />
      <compilerarg value="-marm" />
      <compilerarg value="-mfloat-abi=softfp" />
      <linkerarg value="-fpic" />
      <linkerarg value="-march=armv5te" />
      <linkerarg value="-marm" />
      <linkerarg value="-mfloat-abi=softfp" />
      <linkerarg value="-nostdlib" />
      <linkerarg value="-Bdynamic" />

 compiler.cfg.linux.armv6hf:
      <compilerarg value="-fpic" />
      <compilerarg value="-march=armv6" />
      <compilerarg value="-marm" />
      <compilerarg value="-mfloat-abi=hard" />
      <linkerarg value="-fpic" />
      <linkerarg value="-march=armv6" />
      <linkerarg value="-marm" />
      <linkerarg value="-mfloat-abi=hard" />
      <linkerarg value="-nostdlib" />
      <linkerarg value="-Bdynamic" />

 gluegen-cpptasks-android-armv6.xml:
      <compilerarg value="-fpic" />
      <compilerarg value="-march=armv6" />
      <compilerarg value="-mfloat-abi=softfp" />
      <compilerarg value="-marm" />

      <linkerarg value="-march=armv6" />
      <linkerarg value="-mfloat-abi=softfp" />
      <linkerarg value="-marm" />
      <linkerarg value="-nostdlib" />
      <linkerarg value="-Bdynamic" />