See https://bugs.openjdk.org/browse/JDK-8178689 for some analysis - we can
safely replace the deprecated/obsolete isnanf (which musl doesn't immplement)
with isnan.

https://bugs.gentoo.org/896170
https://bugs.gentoo.org/829344
--- a/intonation/tilt/tilt_utils.cc
+++ b/intonation/tilt/tilt_utils.cc
@@ -133,7 +133,7 @@ float rfc_to_t_tilt(EST_Features &e)
 {
     float t_tilt;
     t_tilt = (rfc_to_a_tilt(e) + rfc_to_d_tilt(e)) / 2;
-    if (isnanf(t_tilt))
+    if (isnan(t_tilt))
 	t_tilt = 0.0;
     return t_tilt;
 }
--- a/sigpr/pda/smooth_pda.cc
+++ b/sigpr/pda/smooth_pda.cc
@@ -112,7 +112,7 @@ void smooth_portion(EST_Track &c, EST_Features &op)
 
     for (i = 0; i < c.num_frames(); ++i)
     {   // occasionally NaNs result...
-	if (isnanf(a[i]))
+	if (isnan(a[i]))
 	{
 	    c.set_break(i);
 	    c.a(i) = 0.0;
--- a/sigpr/sigpr_frame.cc
+++ b/sigpr/sigpr_frame.cc
@@ -314,7 +314,7 @@ void lpc2cep(const EST_FVector &lpc, EST_FVector &cep)
     for (n = 0; n < cep.length(); n++) 
     {
 	// check if NaN -- happens on some frames of silence
-	if (isnanf(cep[n]) ) cep[n] = 0.0;
+	if (isnan(cep[n]) ) cep[n] = 0.0;
 	
 	if (cep[n] >  MAX_ABS_CEPS){
 	    cerr << "WARNING : cepstral coeff " << n << " was " << 
--- a/stats/confusion.cc
+++ b/stats/confusion.cc
@@ -138,7 +138,7 @@ void print_confusion(const EST_FMatrix &a, EST_StrStr_KVL &list,
 	cout.precision(3);
 	cout.setf(ios::right);
 //	cout.setf(ios::fixed, ios::floatfield);
-	if (isnanf(correct(i)))
+	if (isnan(correct(i)))
 	    cout << endl;
 	else
 	    cout << correct(i) << endl;
--- a/include/EST_math.h
+++ b/include/EST_math.h
@@ -81,12 +81,6 @@ extern "C" {
 #define isnanf(X) isnan(X)
 #endif
 
-/* Linux (and presumably Hurd too as Linux is GNU libc based) */
-/* Sorry I haven't confirmed this cpp symbol yet              */
-#if defined(linux)
-#define isnanf(X) __isnanf(X)
-#endif
-
 /* OS/2 with gcc EMX */
 #if defined(__EMX__)
 #define isnanf(X) isnan(X)