patch 8.2.4756: build error without the +eval feature

Problem:    Build error without the +eval feature.
Solution:   Adjust #ifdefs.

src/misc1.c

@@ -1899,7 +1899,6 @@ vim_getenv(char_u *name, int *mustfree)
     return p;
 }
 
-#if defined(FEAT_EVAL) || defined(PROTO)
     void
 vim_unsetenv(char_u *var)
 {
@@ -1925,6 +1924,7 @@ vim_unsetenv_ext(char_u *var)
 	didset_vimruntime = FALSE;
 }
 
+#if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * Set environment variable "name" and take care of side effects.
  */

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4756,
 /**/
     4755,
 /**/