rtlib: string and wstring conversions

In previous commit (Skyfish) converting between string and wstring uses multi-byte & wide character
functions wctombs() & mbtowcs() However, on DOS wctombs() & mbtowcs() just map to memcpy, so keep
the previous string length calculation for DOS only.

(cherry picked from commit bade534)

Author: jayrm

changelog.txt

@@ -17,6 +17,7 @@ Version 1.07.2
 - github #258: on windows directx and gdi drivers, only show window after intialization is complete (adeyblue)
 - sf.net #925: CSIGN/CUNSG preserve size when converting pointers on 64-bit and implict conversion of STEP value in FOR...NEXT statement
 - github #122: gfxlib2: linux GFX_NO_FRAME + GFX_OPENGL freezing at exit due to a dead lock between exit routines
+- use the multi-byte & wide character functions wctombs() & mbtowcs() when converting between string and wstring (Skyfish)
 
 
 Version 1.07.1

src/rtlib/strw_convfrom_str.c

@@ -61,7 +61,13 @@ FBCALL FB_WCHAR *fb_StrToWstr( const char *src )
     if( src == NULL )
         return NULL;
 
+#if defined HOST_DOS
+    /* on DOS, mbstowcs() simply calls memcpy() and won't compute
+       length  see fb_unicode.h */
+    chars = strlen( src );
+#else
     chars = mbstowcs( NULL, src, 0 );
+#endif
     if( chars == 0 )
         return NULL;
 

src/rtlib/strw_convto_str.c

@@ -72,7 +72,13 @@ FBCALL FBSTRING *fb_WstrToStr( const FB_WCHAR *src )
     if( src == NULL )
         return &__fb_ctx.null_desc;
 
+#if defined HOST_DOS
+    /* on DOS, wcstombs() simply calls memcpy() and won't compute
+       length  see fb_unicode.h */
+    chars = fb_wstr_Len( src );
+#else
     chars = wcstombs( NULL, src, 0 );
+#endif
     if( chars == 0 )
         return &__fb_ctx.null_desc;