[libxml2] Change preprocessor OS tests to __linux__

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 2cdaaab11ce3fc855361b3267bc25fe3b9fa1f6f
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Thu Sep 14 21:30:51 2017 +0200

    Change preprocessor OS tests to __linux__
    
    "linux" without leading underscores is deprecated and less reliable.

 .travis.yml  |    2 +-
 elfgcchack.h |    2 +-
 libxml.h     |    2 +-
 nanohttp.c   |    2 +-
 threads.c    |    4 ++--
 5 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/.travis.yml b/.travis.yml
index 5975976..6055b9a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,7 +11,7 @@ matrix:
     # GNU extensions as possible. -Dlinux is required to make the weak
     # pthread symbols work.
     - compiler: gcc
-      env: CFLAGS="-O2 -std=c89 -D_POSIX_C_SOURCE=200809L -Dlinux"
+      env: CFLAGS="-O2 -std=c89 -D_POSIX_C_SOURCE=200809L"
     # clang with AddressSanitizer and UndefinedBehaviorSanitizer.
     - compiler: clang
       dist: trusty
diff --git a/elfgcchack.h b/elfgcchack.h
index 8c52884..5ac93bf 100644
--- a/elfgcchack.h
+++ b/elfgcchack.h
@@ -11,7 +11,7 @@
 #ifdef IN_LIBXML
 #ifdef __GNUC__
 #ifdef PIC
-#ifdef linux
+#ifdef __linux__
 #if (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || (__GNUC__ > 3)
 
 #include "libxml/c14n.h"
diff --git a/libxml.h b/libxml.h
index 88e515f..f13e9de 100644
--- a/libxml.h
+++ b/libxml.h
@@ -101,7 +101,7 @@ int xmlNop(void);
 #ifdef IN_LIBXML
 #ifdef __GNUC__
 #ifdef PIC
-#ifdef linux
+#ifdef __linux__
 #if (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || (__GNUC__ > 3)
 #include "elfgcchack.h"
 #endif
diff --git a/nanohttp.c b/nanohttp.c
index b911f9c..0533102 100644
--- a/nanohttp.c
+++ b/nanohttp.c
@@ -1130,7 +1130,7 @@ xmlNanoHTTPConnectHost(const char *host, int port)
  * extraction code. it work on Linux, if it work on your platform
  * and one want to enable it, send me the defined(foobar) needed
  */
-#if defined(HAVE_NETDB_H) && defined(HOST_NOT_FOUND) && defined(linux)
+#if defined(HAVE_NETDB_H) && defined(HOST_NOT_FOUND) && defined(__linux__)
            const char *h_err_txt = "";
 
            switch (h_errno) {
diff --git a/threads.c b/threads.c
index 8c57263..e52f263 100644
--- a/threads.c
+++ b/threads.c
@@ -48,7 +48,7 @@
 
 static int libxml_is_threaded = -1;
 #if defined(__GNUC__) && defined(__GLIBC__)
-#ifdef linux
+#ifdef __linux__
 #if (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || (__GNUC__ > 3)
 #pragma weak pthread_once
 #pragma weak pthread_getspecific
@@ -68,7 +68,7 @@ static int libxml_is_threaded = -1;
 #pragma weak pthread_key_delete
 #pragma weak pthread_cond_signal
 #endif
-#endif /* linux */
+#endif /* __linux__ */
 #endif /* defined(__GNUC__) && defined(__GLIBC__) */
 #endif /* HAVE_PTHREAD_H */