krb5 commit [krb5-1.18]: Fix Linux build error with musl libc

[Greg Hudson]

https://github.com/krb5/krb5/commit/062dbfaa9c66d29bca3e7071fcaba336172987b9
commit 062dbfaa9c66d29bca3e7071fcaba336172987b9
Author: TBK <tbk at jjtc.eu>
Date:   Wed Feb 26 21:12:45 2020 +0100

    Fix Linux build error with musl libc
    
    Commit bf5953c549a6d279977df69ffe89b2ba51460eaf caused a build failure
    on non-glibc Linux build environments.  Change the conditionalization
    so that __GLIBC_PREREQ will only be used if it is defined.
    
    [ghudson at mit.edu: simplified conditionals; rewrote commit message]
    
    (cherry picked from commit cbdbc8d00d31344fafe00e0fdf984e04e631f7c4)
    
    ticket: 8880
    version_fixed: 1.18.1

 src/util/support/plugins.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/src/util/support/plugins.c b/src/util/support/plugins.c
index 3329db7..1644d16 100644
--- a/src/util/support/plugins.c
+++ b/src/util/support/plugins.c
@@ -62,8 +62,7 @@
  * dlopen() with RTLD_NODELETE, we weren't going to unload the plugin objects
  * anyway.
  */
-#ifdef __linux__
-#include <features.h>
+#ifdef __GLIBC__PREREQ
 #if ! __GLIBC_PREREQ(2, 25)
 #define dlclose(x)
 #endif