configure.ac: Fix typos.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Alejandro PiƱeiro <apinheiro@igalia.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Cc: <mesa-stable@lists.freedesktop.org>
diff --git a/configure.ac b/configure.ac
index 957d15d..e42fcff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -724,7 +724,7 @@
 dnl
 AC_ARG_ENABLE([asm],
     [AS_HELP_STRING([--disable-asm],
-        [disable assembly usage @<:@default=enabled on supported plaforms@:>@])],
+        [disable assembly usage @<:@default=enabled on supported platforms@:>@])],
     [enable_asm="$enableval"],
     [enable_asm=yes]
 )
@@ -2146,7 +2146,7 @@
 dnl
 AC_ARG_WITH([egl-platforms],
     [AS_HELP_STRING([--with-egl-platforms@<:@=DIRS...@:>@],
-        [DEPRECATED: use --with-plaforms instead@<:@default=auto@:>@])],
+        [DEPRECATED: use --with-platforms instead@<:@default=auto@:>@])],
     [with_egl_platforms="$withval"],
     [with_egl_platforms=auto])
 
@@ -2161,7 +2161,7 @@
         with_egl_platforms=""
     fi
 else
-    AC_MSG_WARN([--with-egl-platforms is deprecated. Use --with-plaforms instead.])
+    AC_MSG_WARN([--with-egl-platforms is deprecated. Use --with-platforms instead.])
 fi
 
 dnl