libarchive: treat one "FIXME: avoid seek"

function                                             old     new   delta
xmalloc_read_with_initial_buf                          -     205    +205
setup_transformer_on_fd                              154     150      -4
xmalloc_open_zipped_read_close                       143     135      -8
xmalloc_read                                         201      10    -191
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/3 up/down: 205/-203)            Total: 2 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/read_printf.c b/libbb/read_printf.c
index b6a17cc..cb582c0 100644
--- a/libbb/read_printf.c
+++ b/libbb/read_printf.c
@@ -102,10 +102,9 @@
 
 // Read (potentially big) files in one go. File size is estimated
 // by stat. Extra '\0' byte is appended.
-void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
+void* FAST_FUNC xmalloc_read_with_initial_buf(int fd, size_t *maxsz_p, char *buf, size_t total)
 {
-	char *buf;
-	size_t size, rd_size, total;
+	size_t size, rd_size;
 	size_t to_read;
 	struct stat st;
 
@@ -118,8 +117,6 @@
 	/* In order to make such files readable, we add small const */
 	size = (st.st_size | 0x3ff) + 1;
 
-	total = 0;
-	buf = NULL;
 	while (1) {
 		if (to_read < size)
 			size = to_read;
@@ -148,6 +145,11 @@
 	return buf;
 }
 
+void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
+{
+	return xmalloc_read_with_initial_buf(fd, maxsz_p, NULL, 0);
+}
+
 #ifdef USING_LSEEK_TO_GET_SIZE
 /* Alternatively, file size can be obtained by lseek to the end.
  * The code is slightly bigger. Retained in case fstat approach