libbb/loop: fix compile failure (name collision)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/loop.c b/libbb/loop.c
index 95c4a34..a0c5d02 100644
--- a/libbb/loop.c
+++ b/libbb/loop.c
@@ -112,7 +112,7 @@
 
 #if ENABLE_TRY_LOOP_CONFIGURE || ENABLE_LOOP_CONFIGURE
 # define LOOP_CONFIGURE 0x4C0A
-struct loop_config {
+struct bb_loop_config {
 	uint32_t fd;
 	uint32_t block_size;
 	struct loop_info64 info;
@@ -128,7 +128,7 @@
 {
 	int rc;
 #if ENABLE_TRY_LOOP_CONFIGURE || ENABLE_LOOP_CONFIGURE
-	struct loop_config lconfig;
+	struct bb_loop_config lconfig;
 # define loopinfo lconfig.info
 #else
 	bb_loop_info loopinfo;