Fix build with musl

[Andrew S. <bi...@gm...>]

When musl is used instead of glibc, oprofile build fails because it
uses glibc-specific FTW extension: FTW_ACTIONRETVAL for custom
__delete_old_previous_sample_data return codes and FTW_STOP,
FTW_CONTINUE for such return codes. Musl supports only POSIX ftw, so
build fails.

However, this extension is not really needed by oprofile, because
FTW_SKIP_* are not used and {FTW_STOP,FTW_CONTINUE} can be handled
by standard return codes {1,0} (more precisely standard defines
{!0,0}, but in glibc FTW_STOP = 1, so I keep this value).

Signed-off-by: Andrew Savchenko <bi...@gm...>
---
 pe_profiling/operf.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pe_profiling/operf.cpp b/pe_profiling/operf.cpp
index 06a0ea3c..1b882b7c 100644
--- a/pe_profiling/operf.cpp
+++ b/pe_profiling/operf.cpp
@@ -860,9 +860,9 @@ static int __delete_old_previous_sample_data(const char *fpath,
 {
    if (remove(fpath)) {
        perror("sample data removal error");
-       return FTW_STOP;
+       return 1;
    } else {
-       return FTW_CONTINUE;
+       return 0;
    }
 }

@@ -897,7 +897,7 @@ static void convert_sample_data(void)
        return;

    if (!operf_options::append) {
-                int flags = FTW_DEPTH | FTW_ACTIONRETVAL;
+                int flags = FTW_DEPTH;
        errno = 0;
        if (nftw(previous_sampledir.c_str(), __delete_old_previous_sample_data, 32, flags) !=0 &&
                errno != ENOENT) {
--
2.24.0

Best regards,
Andrew Savchenko