misc: Fix coding style for struct's opening braces

The systemc dir was not included in this fix.

First it was identified that there were only occurrences
at 0, 1, 2 and 3 levels of indentation (and a single
occurrence of 2 and 3 spaces), using:

    grep -nrE --exclude-dir=systemc \
        "^ *struct [A-Za-z].* {$" src/

Then the following commands were run to replace:

<indent level>struct X ... {

by:

<indent level>struct X ...
<indent level>{

Level 0:
    grep -nrl --exclude-dir=systemc
        "^struct [A-Za-z].* {$" src/ | \
        xargs sed -Ei \
        's/^struct ([A-Za-z].*) \{$/struct \1\n\{/g'

Level 1:
    grep -nrl --exclude-dir=systemc \
        "^    struct [A-Za-z].* {$" src/ | \
        xargs sed -Ei \
        's/^    struct ([A-Za-z].*) \{$/    struct \1\n    \{/g'

and so on.

Change-Id: I362ef58c86912dabdd272c7debb8d25d587cd455
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39017
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/testers/traffic_gen/base.hh

@@ -191,7 +191,8 @@ class BaseTrafficGen : public ClockedObject
     /** Reqs waiting for response **/
     std::unordered_map<RequestPtr,Tick> waitingResp;
 
-    struct StatGroup : public Stats::Group {
+    struct StatGroup : public Stats::Group
+    {
         StatGroup(Stats::Group *parent);
 
         /** Count the number of dropped requests. */

src/cpu/testers/traffic_gen/trace_gen.hh

@@ -63,7 +63,8 @@ class TraceGen : public BaseGen
     /**
      * This struct stores a line in the trace file.
      */
-    struct TraceElement {
+    struct TraceElement
+    {
 
         /** Specifies if the request is to be a read or a write */
         MemCmd cmd;

src/cpu/testers/traffic_gen/traffic_gen.hh

@@ -100,7 +100,8 @@ class TrafficGen : public BaseTrafficGen
     size_t nextState();
 
     /** Struct to represent a probabilistic transition during parsing. */
-    struct Transition {
+    struct Transition
+    {
         uint32_t from;
         uint32_t to;
         double p;