httpd: simplify insane conf file parser

function                                             old     new   delta
bb_simplify_abs_path_inplace                           -      98     +98
parse_expr                                           824     832      +8
passwd_main                                         1025    1027      +2
evalvar                                             1374    1376      +2
parse_command                                       1463    1460      -3
bb_simplify_path                                     137      55     -82
parse_conf                                          1572    1422    -150
------------------------------------------------------------------------------
(add/remove: 3/2 grow/shrink: 3/3 up/down: 126/-251)         Total: -125 bytes

diff --git a/include/libbb.h b/include/libbb.h
index 4de3e79..3a94a00 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1093,6 +1093,8 @@
 void print_signames(void) FAST_FUNC;
 
 char *bb_simplify_path(const char *path) FAST_FUNC;
+/* Returns ptr to NUL */
+char *bb_simplify_abs_path_inplace(char *path) FAST_FUNC;
 
 #define FAIL_DELAY 3
 extern void bb_do_delay(int seconds) FAST_FUNC;