misc: Rename Debug namespace as debug

As part of recent decisions regarding namespace
naming conventions, all namespaces will be changed
to snake case.

gem5::Debug became gem5::debug.

Change-Id: Ic04606baab3317d2e58ab3ca9b37fc201c406ee8
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47305
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/SConscript

@@ -1154,12 +1154,15 @@ def makeDebugFlagCC(target, source, env):
 
     # file header
     code('''
+#include "base/compiler.hh" // For namespace deprecation
 #include "base/debug.hh"
 
 namespace gem5
 {
 
-namespace Debug {
+GEM5_DEPRECATED_NAMESPACE(Debug, debug);
+namespace debug
+{
 
 ''')
 
@@ -1196,7 +1199,7 @@ namespace Debug {
 
     code.append(comp_code)
     code()
-    code('} // namespace Debug')
+    code('} // namespace debug')
     code('} // namespace gem5')
 
     code.write(str(target[0]))
@@ -1214,10 +1217,14 @@ def makeDebugFlagHH(target, source, env):
 #ifndef __DEBUG_${name}_HH__
 #define __DEBUG_${name}_HH__
 
+#include "base/compiler.hh" // For namespace deprecation
+
 namespace gem5
 {
 
-namespace Debug {
+GEM5_DEPRECATED_NAMESPACE(Debug, debug);
+namespace debug
+{
 ''')
 
     if compound:
@@ -1232,7 +1239,7 @@ namespace Debug {
         code('extern SimpleFlag& $name;')
 
     code('''
-} // namespace Debug
+} // namespace debug
 } // namespace gem5
 
 #endif // __DEBUG_${name}_HH__