msun: update Clang bug reference in fma test

LLVM bugzilla bug 8100 became issue #8472 with the migration to GitHub.

llvm/llvm-project#8472

Author: emaste

lib/msun/src/s_fma.c

@@ -244,7 +244,7 @@ fma(double x, double y, double z)
 		zs = copysign(DBL_MIN, zs);
 
 	fesetround(FE_TONEAREST);
-	/* work around clang bug 8100 */
+	/* work around clang issue #8472 */
 	volatile double vxs = xs;
 
 	/*
@@ -278,7 +278,7 @@ fma(double x, double y, double z)
 		 * rounding modes.
 		 */
 		fesetround(oround);
-		/* work around clang bug 8100 */
+		/* work around clang issue #8472 */
 		volatile double vrlo = r.lo;
 		adj = vrlo + xy.lo;
 		return (ldexp(r.hi + adj, spread));

lib/msun/src/s_fmal.c

@@ -225,7 +225,7 @@ fmal(long double x, long double y, long double z)
 		zs = copysignl(LDBL_MIN, zs);
 
 	fesetround(FE_TONEAREST);
-	/* work around clang bug 8100 */
+	/* work around clang issue #8472 */
 	volatile long double vxs = xs;
 
 	/*
@@ -259,7 +259,7 @@ fmal(long double x, long double y, long double z)
 		 * rounding modes.
 		 */
 		fesetround(oround);
-		/* work around clang bug 8100 */
+		/* work around clang issue #8472 */
 		volatile long double vrlo = r.lo;
 		adj = vrlo + xy.lo;
 		return (ldexpl(r.hi + adj, spread));