libc: Use explicit fallthrough annotations

Replace remaining comment-based switch fall-through annotations with
explicit compiler-supported ones as defined by __PICOLIBC_FALLTHROUGH.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

newlib/libc/stdio/vfscanf.c

@@ -1576,7 +1576,7 @@ _SVFSCANF (
 			}
 		      goto fskip;
 		    }
-		  /* Fall through.  */
+                  __PICOLIBC_FALLTHROUGH;
 		case '1':
 		case '2':
 		case '3':

newlib/libc/stdio/vfwscanf.c

@@ -1330,7 +1330,7 @@ _SVFWSCANF (
 			}
 		      goto fskip;
 		    }
-		  /* Fall through.  */
+                  __PICOLIBC_FALLTHROUGH;
 		case L'1':
 		case L'2':
 		case L'3':

newlib/libc/time/strftime.c

@@ -1026,7 +1026,7 @@ __strftime (CHAR *s, size_t maxsize, const CHAR *format,
 		break;
 	    }
 #endif /* _WANT_C99_TIME_FORMATS */
-	  /*FALLTHRU*/
+	  __PICOLIBC_FALLTHROUGH;
 	case CQ('k'):	/* newlib extension */
 	  len = t_snprintf (&s[count], maxsize - count,
 			  *format == CQ('k') ? CQ("%2d") : CQ("%.2d"),
@@ -1036,7 +1036,7 @@ __strftime (CHAR *s, size_t maxsize, const CHAR *format,
 	case CQ('l'):	/* newlib extension */
 	  if (alt == CQ('O'))
 	    alt = CQ('\0');
-	  /*FALLTHRU*/
+	  __PICOLIBC_FALLTHROUGH;
 	case CQ('I'):
 	  {
 	    register int  h12;

newlib/libm/ld/ld80/e_lgammal_r.c

@@ -391,15 +391,19 @@ lgammal_r(long double x, int *signgamp)
       switch (i)
 	{
 	case 7:
-	  z *= (y + 6.0L);	/* FALLTHRU */
+	  z *= (y + 6.0L);
+          __PICOLIBC_FALLTHROUGH;
 	case 6:
-	  z *= (y + 5.0L);	/* FALLTHRU */
+	  z *= (y + 5.0L);
+          __PICOLIBC_FALLTHROUGH;
 	case 5:
-	  z *= (y + 4.0L);	/* FALLTHRU */
+	  z *= (y + 4.0L);
+          __PICOLIBC_FALLTHROUGH;
 	case 4:
-	  z *= (y + 3.0L);	/* FALLTHRU */
+	  z *= (y + 3.0L);
+          __PICOLIBC_FALLTHROUGH;
 	case 3:
-	  z *= (y + 2.0L);	/* FALLTHRU */
+	  z *= (y + 2.0L);
 	  r += logl (z);
 	  break;
 	}

newlib/libm/math/sr_lgamma.c

@@ -320,15 +320,19 @@ __math_lgamma_r(__float64 x, int *signgamp, int *divzero)
         z = one; /* lgamma(1+s) = log(s) + lgamma(s) */
         switch (i) {
         case 7:
-            z *= (y + 6.0); /* FALLTHRU */
+            z *= (y + 6.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 6:
-            z *= (y + 5.0); /* FALLTHRU */
+            z *= (y + 5.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 5:
-            z *= (y + 4.0); /* FALLTHRU */
+            z *= (y + 4.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 4:
-            z *= (y + 3.0); /* FALLTHRU */
+            z *= (y + 3.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 3:
-            z *= (y + 2.0); /* FALLTHRU */
+            z *= (y + 2.0);
             r += log64(z);
             break;
         }

newlib/libm/math/srf_lgamma.c

@@ -252,15 +252,19 @@ __math_lgammaf_r(float x, int *signgamp, int *divzero)
         z = one; /* lgamma(1+s) = log(s) + lgamma(s) */
         switch (i) {
         case 7:
-            z *= (y + (float)6.0); /* FALLTHRU */
+            z *= (y + (float)6.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 6:
-            z *= (y + (float)5.0); /* FALLTHRU */
+            z *= (y + (float)5.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 5:
-            z *= (y + (float)4.0); /* FALLTHRU */
+            z *= (y + (float)4.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 4:
-            z *= (y + (float)3.0); /* FALLTHRU */
+            z *= (y + (float)3.0);
+	  __PICOLIBC_FALLTHROUGH;
         case 3:
-            z *= (y + (float)2.0); /* FALLTHRU */
+            z *= (y + (float)2.0);
             r += logf(z);
             break;
         }