If only BB_DPKG was enabled in Config.h, busybox would not build; it'd say:

  dpkg.c:18: #error It looks like you are using libc5, which does not support
  dpkg.c:19: #error tfind().  tfind() is used by busybox dpkg.
  dpkg.c:20: #error Please disable BB_DPKG.  Sorry.
This was fixed by changing the || to an && in the preprocessor.
(We've changed the logic in there too many times.)
Found using multibuild.pl.

2 files changed, 2 insertions, 2 deletions

diff --git a/archival/dpkg.c b/archival/dpkg.c
index 4720a8820..d65081715 100644
--- a/archival/dpkg.c
+++ b/archival/dpkg.c
@@ -14,7 +14,7 @@
 
 /* Stupid libc doesn't have a reliable way for use to know 
  * that libc5 is being used.   Assume this is good enough */ 
-#if !defined __GLIBC__ || !defined __UCLIBC__
+#if !defined __GLIBC__ && !defined __UCLIBC__
 #error It looks like you are using libc5, which does not support
 #error tfind().  tfind() is used by busybox dpkg.
 #error Please disable BB_DPKG.  Sorry.
diff --git a/dpkg.c b/dpkg.c
index 4720a8820..d65081715 100644
--- a/dpkg.c
+++ b/dpkg.c
@@ -14,7 +14,7 @@
 
 /* Stupid libc doesn't have a reliable way for use to know 
  * that libc5 is being used.   Assume this is good enough */ 
-#if !defined __GLIBC__ || !defined __UCLIBC__
+#if !defined __GLIBC__ && !defined __UCLIBC__
 #error It looks like you are using libc5, which does not support
 #error tfind().  tfind() is used by busybox dpkg.
 #error Please disable BB_DPKG.  Sorry.