musl does not provice feenableexcept and fedisableexcept. Those calls have
only been used on linux so far. This patch extends the #ifdef logic to only use
them on Linux if additionally glibc is used.
diff --git a/src/OSD/OSD_signal.cxx b/src/OSD/OSD_signal.cxx
index 0545d7496d..475edd0f71 100644
--- a/src/OSD/OSD_signal.cxx
+++ b/src/OSD/OSD_signal.cxx
@@ -744,7 +744,7 @@ LONG _osd_debug(void)
   // POSIX threads
   #include <pthread.h>
 
-  #ifdef __linux__
+  #ifdef __linux__ && defined(__GLIBC__)
     #include <cfenv>
   // #include  <fenv.h>
   #endif
@@ -866,7 +866,7 @@ static void Handler(const int theSignal)
     case SIGFPE:
       sigaddset(&set, SIGFPE);
       sigprocmask(SIG_UNBLOCK, &set, NULL);
-  #ifdef __linux__
+  #ifdef __linux__ && defined(__GLIBC__)
       OSD::SetFloatingSignal(Standard_True);
   #endif
   #if (!defined(__sun)) && (!defined(SOLARIS))