contrib/bc: fix build with GCC

Building with GCC failed with the following error message:

 error: to be safe all intermediate pointers in cast from 'char **'
 to 'const char **' must be 'const' qualified [-Werror=cast-qual]

This was caused by main() being declared with "char *argv[]" as the
3rd parameter, but argv later being passed cast to "const char**":

113 |     if (BC_IS_BC) s = bc_main(argc, (const char**) argv);
    |                                      ^

This is fixed by declaring the 3rd parameter of main() as "const
char *argv[]".

Reported by:	CI
MFC after:	3 days

(cherry picked from commit ef5752762ba9ec54d5c02023167d24bcdbb45fd7)

vendor/bc: upgrade to version 7.0.1

This update fixes building bc on FreeBSD with non-default compilers
(GCC-12, GCC-13). GCC warned about casting argv from non-const to const
and since warnings are treated as errors, the build failed.

(cherry picked from commit 1e19146fc7692f59e8dfc5da7957e938cd0b81b8)
(cherry picked from commit 5b0dc991093c82824f6fe566af947f64f5072264)

contrib/bc/NEWS.md

@@ -1,5 +1,11 @@
 # News
 
+## 7.0.1
+
+This is a production release that fixes a warning using GCC on FreeBSD.
+
+Other users do ***NOT*** need to upgrade.
+
 ## 7.0.0
 
 This is a production release to fix three bugs.

contrib/bc/include/version.h

@@ -37,6 +37,6 @@
 #define BC_VERSION_H
 
 /// The current version.
-#define VERSION 7.0.0
+#define VERSION 7.0.1
 
 #endif // BC_VERSION_H

contrib/bc/src/main.c

@@ -54,7 +54,7 @@
 #include <dc.h>
 
 int
-main(int argc, char* argv[])
+main(int argc, const char* argv[])
 {
 	BcStatus s;
 	char* name;