Fix architecture detection on ppc64le

juce_runtime_arch_detection.cpp currently identifies ppc64le as ppc64,
which causes it to use the directory name `ppc64-linux` for VST 3 plugin
contents. However, VST 3 specifies that `uname -m` should be used as the
first component of the directory name, which on 64-bit little-endian
PowerPC is `ppc64le`.

Currently, this causes problems building VST 3 plugins on this platform,
as the VST 3 SDK expects the module directory to be named
`ppc64le-linux`.

This commit adds an additional endianness check when 64-bit PowerPC is
detected, outputting `ppc64` or `ppc64le` as appropriate.

extras/Build/CMake/juce_runtime_arch_detection.cpp

@@ -62,7 +62,11 @@
 #elif defined(__ppc__) || defined(__ppc) || defined(__powerpc__) || defined(_ARCH_COM) || defined(_ARCH_PWR) || defined(_ARCH_PPC) || defined(_M_MPPC) || defined(_M_PPC)
 
   #if defined(__ppc64__) || defined(__powerpc64__) || defined(__64BIT__)
-    #error JUCE_ARCH ppc64
+    #ifdef __LITTLE_ENDIAN__
+      #error JUCE_ARCH ppc64le
+    #else
+      #error JUCE_ARCH ppc64
+    #endif
   #else
     #error JUCE_ARCH ppc
   #endif