Make sure that a recent dsp compiler warnings fix is only applied to newer gcc versions

modules/juce_dsp/native/juce_avx_SIMDNativeOps.h

@@ -31,7 +31,7 @@ namespace dsp
 
 #ifndef DOXYGEN
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wignored-attributes"
 #endif
@@ -705,7 +705,7 @@ struct SIMDNativeOps<uint64_t>
 
 #endif
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic pop
 #endif
 

modules/juce_dsp/native/juce_neon_SIMDNativeOps.h

@@ -31,7 +31,7 @@ namespace dsp
 
 #ifndef DOXYGEN
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wignored-attributes"
 #endif
@@ -467,7 +467,7 @@ struct SIMDNativeOps<double>
 
 #endif
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic pop
 #endif
 

modules/juce_dsp/native/juce_sse_SIMDNativeOps.h

@@ -31,7 +31,7 @@ namespace dsp
 
 #ifndef DOXYGEN
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wignored-attributes"
 #endif
@@ -872,7 +872,7 @@ struct SIMDNativeOps<uint64_t>
 
 #endif
 
-#if JUCE_GCC
+#if JUCE_GCC && (__GNUC__ >= 6)
  #pragma GCC diagnostic pop
 #endif