https://bugs.gentoo.org/779406

commit e55f6880d6bb649b2f1bd55c31bd4ba6265ccae0
Author: orbea <orbea@riseup.net>
Date:   Tue Mar 30 11:54:33 2021 -0700

    build: Fix undefined references for libm.

diff --git a/Makefile.am b/Makefile.am
index 16d29ea..09a51bb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -22,4 +22,4 @@ libaurora_la_SOURCES =		\
 	./src/config.h
 
 libaurora_la_LDFLAGS = -module -avoid-version -no-undefined
-libaurora_la_LIBADD =  $(GTK_LIBS)
+libaurora_la_LIBADD = $(GTK_LIBS) $(LIBM)
diff --git a/configure.ac b/configure.ac
index b1c35e9..9b446c3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,6 +20,9 @@ AC_ARG_ENABLE(animation, 	[  --enable-animation      compile aurora with animati
 
 PKG_CHECK_MODULES(GTK, gtk+-2.0 >= 2.10.0,,AC_MSG_ERROR([GTK+-2.10 is required to compile aurora]))
 
+AC_CHECK_LIBM
+AC_SUBST([LIBM])
+
 AC_SUBST(GTK_CFLAGS)
 AC_SUBST(GTK_LIBS)