Use a semicolon to separate frames

Use a semicolon instead of a comma to separate frames in the
flamegraph input.  Commas can appear in demangled C++ function
names (e.g. foo(int, int) ) so using commas to separate frames
can confuse the parser.

flamegraph.pl

@@ -135,8 +135,8 @@ sub color {
 
 sub flow {
 	my ($a, $b, $v) = @_;
-	my @A = split ",", $a;
-	my @B = split ",", $b;
+	my @A = split ";", $a;
+	my @B = split ";", $b;
 
 	my $len_a = $#A;
 	my $len_b = $#B;

stackcollapse-perf.pl

@@ -68,7 +68,7 @@ sub remember_stack {
 	chomp;
 
 	if (m/^$/) {
-		remember_stack(join(",", @stack), 1) if @stack;
+		remember_stack(join(";", @stack), 1) if @stack;
 		undef @stack;
 		next;
 	}

stackcollapse-stap.pl

@@ -64,7 +64,7 @@ sub remember_stack {
 	chomp;
 
 	if (m/^\s*(\d+)+$/) {
-		remember_stack(join(",", @stack), $1);
+		remember_stack(join(";", @stack), $1);
 		@stack = ();
 		next;
 	}

stackcollapse.pl

@@ -66,7 +66,7 @@ sub remember_stack {
 	chomp;
 
 	if (m/^\s*(\d+)+$/) {
-		remember_stack(join(",", @stack), $1);
+		remember_stack(join(";", @stack), $1);
 		@stack = ();
 		next;
 	}