Fix "control reaches end of non-void function" errors in testsuite

When running the testsuite with clang, a number of testcases fail to
build with the following errors:
  warning: control reaches end of non-void function [-Wreturn-type]
  warning: control may reach end of non-void function [-Wreturn-type]

This prevents a number of testcases from executing.  This commit fixes.

gdb/testsuite/ChangeLog:

	* gdb.base/info-os.c (main): Add return statement.
	* gdb.base/info_minsym.c (minsym_fun): Likewise.
	* gdb.base/large-frame-2.c (func): Likewise.
	* gdb.base/pr10179-a.c (foo1, bar1): Likewise.
	* gdb.base/pr10179-b.c (foo2): Likewise.
	* gdb.base/valgrind-disp-step.c (foo): Likewise.
	* gdb.base/watch-cond.c (func): Likewise.
	* gdb.multi/goodbye.c (verylongfun): Likewise.
	* gdb.multi/hello.c (commonfun): Likewise.
	* gdb.python/py-finish-breakpoint.c (call_longjmp): Likewise.
	* gdb.threads/fork-plus-threads.c (thread_func): Likewise.
	* gdb.threads/forking-threads-plus-breakpoint.c (thread_forks):
	Likewise.
	* gdb.threads/hand-call-new-thread.c (foo): Likewise.
	* gdb.threads/interrupt-while-step-over.c (child_function):
	Likewise.
	* gdb.trace/actions-changed.c (end): Likewise.

7 files changed, 9 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/info-os.c b/gdb/testsuite/gdb.base/info-os.c
index f08407f02f2..5b88c2661ee 100644
--- a/gdb/testsuite/gdb.base/info-os.c
+++ b/gdb/testsuite/gdb.base/info-os.c
@@ -48,6 +48,8 @@ thread_proc (void *args)
 {
   pthread_mutex_lock (&mutex);
   pthread_mutex_unlock (&mutex);
+
+  return NULL;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/info_minsym.c b/gdb/testsuite/gdb.base/info_minsym.c
index b4e3a3f3391..6f774b6fe68 100644
--- a/gdb/testsuite/gdb.base/info_minsym.c
+++ b/gdb/testsuite/gdb.base/info_minsym.c
@@ -20,6 +20,7 @@ static int minsym_var;
 static int minsym_fun (void)
 {
    minsym_var++;
+   return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/large-frame-2.c b/gdb/testsuite/gdb.base/large-frame-2.c
index bc2cc8482aa..7a88f57c5cd 100644
--- a/gdb/testsuite/gdb.base/large-frame-2.c
+++ b/gdb/testsuite/gdb.base/large-frame-2.c
@@ -22,4 +22,5 @@ func (void)
 {
   int a[4096];
   blah (a);
+  return 0;
 }
diff --git a/gdb/testsuite/gdb.base/pr10179-a.c b/gdb/testsuite/gdb.base/pr10179-a.c
index 56bce9df92e..584b1bc32a4 100644
--- a/gdb/testsuite/gdb.base/pr10179-a.c
+++ b/gdb/testsuite/gdb.base/pr10179-a.c
@@ -5,11 +5,13 @@ extern int foo2();
 int
 foo1()
 {
+  return 0;
 }
 
 int
 bar1()
 {
+  return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/pr10179-b.c b/gdb/testsuite/gdb.base/pr10179-b.c
index dcc5d9bb8b3..2f328ba5f39 100644
--- a/gdb/testsuite/gdb.base/pr10179-b.c
+++ b/gdb/testsuite/gdb.base/pr10179-b.c
@@ -3,4 +3,5 @@
 int
 foo2()
 {
+  return 0;
 }
diff --git a/gdb/testsuite/gdb.base/valgrind-disp-step.c b/gdb/testsuite/gdb.base/valgrind-disp-step.c
index 3a397ac1619..10de4aa2dc7 100644
--- a/gdb/testsuite/gdb.base/valgrind-disp-step.c
+++ b/gdb/testsuite/gdb.base/valgrind-disp-step.c
@@ -18,6 +18,7 @@
 static int
 foo (void)
 {
+  return 0;
 }
 
 int
diff --git a/gdb/testsuite/gdb.base/watch-cond.c b/gdb/testsuite/gdb.base/watch-cond.c
index fe6fe9028f8..435f0b89c3d 100644
--- a/gdb/testsuite/gdb.base/watch-cond.c
+++ b/gdb/testsuite/gdb.base/watch-cond.c
@@ -23,6 +23,7 @@ int func(int *foo)
   (*foo)++;
   global++;
   global2++;
+  return 0;
 }
 
 void func2(int *foo)