make: fix test for empty command in inference rule

Commit e90345c10 (make: allow empty commands) changed how empty
commands are handled.  This broke the POSIX mode test for
inference rules of the form:

   rule: ;

Adjust the setting of 'semicolon_cmd' to the new reality.

Adds 16-32 bytes.

1 files changed, 1 insertions, 1 deletions

diff --git a/miscutils/make.c b/miscutils/make.c
index 7336afdf3..cc5e7ca92 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -2265,7 +2265,7 @@ input(FILE *fd, int ilevel)
                         free(copy3);
                         *s = '\0';
                 }
-                semicolon_cmd = cp != NULL;
+                semicolon_cmd = cp != NULL && cp->c_cmd[0] != '\0';
 
                 // Create list of prerequisites
                 dp = NULL;