Fix:
error: implicitly declaring library function 'exit' with type 'void (int) __attribute__((noreturn))' [-Werror,-Wimplicit-function-declaration]
--- configure.orig	2022-01-29 00:09:08.000000000 -0600
+++ configure	2022-01-29 00:09:08.000000000 -0600
@@ -10761,6 +10761,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef RTLD_GLOBAL
 #  define LT_DLGLOBAL		RTLD_GLOBAL
@@ -10861,6 +10862,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef RTLD_GLOBAL
 #  define LT_DLGLOBAL		RTLD_GLOBAL
@@ -20500,6 +20502,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 #include <math.h>
+#include <stdlib.h>
 		     #if SIZEOF_FLOAT == 8
 		     float nan = 0.0 / 0.0;
 		     int main() { exit( isnanf(nan) && !finitef(nan) ? 0:1 ); }
@@ -20567,6 +20570,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 #include <math.h>
+#include <stdlib.h>
 		     #if SIZEOF_FLOAT == 8
 		     float inf = 1.0 / 0.0;
 		     int main() { exit( !isnanf(inf) && !finitef(inf) ? 0:1 ); }
@@ -20634,6 +20638,7 @@
 cat confdefs.h >>conftest.$ac_ext
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
+#include <stdlib.h>
 #if SIZEOF_FLOAT == 8
 		      float
 		     #elif SIZEOF_DOUBLE == 8
@@ -20699,6 +20704,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 
+#include <stdlib.h>
 void f(void);
 #define f(a, b...) g(a, 5 , ## b)
 int g(v, w, x, y, z) int v,w,x,y,z; { return v*w*x*y*z; }
@@ -20819,6 +20825,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 #include <setjmp.h>
+#include <stdlib.h>
 		     int main () {
 			jmp_buf b; volatile int c = 0;
 
@@ -20885,6 +20892,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 #include <setjmp.h>
+#include <stdlib.h>
 		     int main () {
 			jmp_buf b; volatile int c = 0;
 
@@ -20967,6 +20975,7 @@
 /* end confdefs.h.  */
 #include <stdio.h>
 		     #include <stdarg.h>
+#include <stdlib.h>
 
 		     int a(fmt, ap)
 			const char *fmt;
@@ -21041,6 +21050,7 @@
 cat >>conftest.$ac_ext <<_ACEOF
 /* end confdefs.h.  */
 
+#include <stdlib.h>
 	int main() {
 #if SIZEOF_FLOAT == 8
 	    float
--- libltdl/configure.orig	2022-01-29 00:09:08.000000000 -0600
+++ libltdl/configure	2022-01-29 00:09:08.000000000 -0600
@@ -10816,6 +10816,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef RTLD_GLOBAL
 #  define LT_DLGLOBAL		RTLD_GLOBAL
@@ -10916,6 +10917,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef RTLD_GLOBAL
 #  define LT_DLGLOBAL		RTLD_GLOBAL
@@ -12035,6 +12037,7 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
 
 #ifdef RTLD_GLOBAL
 #  define LT_DLGLOBAL		RTLD_GLOBAL
