div fixes

- Makefile: don't produce unknown targets
- libtcc.c: tcc_set_linker(): improve parser
- tcc.h: tcc_internal_error(): don't record __FILE__ (for privacy reasons)
- tccgen.c:
  - reject pointer + float operation
  - use 'int level' for builtin_frame/return_address
  - save_regs(): remove VT_ARRAY (confuses riscv64-gen)
- tccpe.c: store just basename of loaded dlls (rather than full path)
- tccpp.c: remove unused TAL defines
- *-link.c: add missing ST_FUNC
- i386-gen.c: fix thiscall
- riscv64-asm.c/arm-asm.c: stay simple C89
  - avoid .designators, decl after statement
  - avoid multiple instances of same static const objects
  - use skip() instead of next() & expect()
  - use cstr_printf() instead of snprintf() & cstr_cat()
  - tcc_error(), expect(): never return

Author: grischka

Makefile

@@ -198,6 +198,7 @@ DEFINES += $(if $(ELF-$T),-DCONFIG_TCC_ELFINTERP="\"$(ELF-$T)\"")
 DEFINES += $(DEF-$(or $(findstring win,$T),unx))
 
 ifneq ($(X),)
+$(if $(DEF-$T),,$(error error: unknown target: '$T'))
 DEF-all += -DCONFIG_TCC_CROSSPREFIX="\"$X\""
 ifneq ($(CONFIG_WIN32),yes)
 DEF-win += -DCONFIG_TCCDIR="\"$(tccdir)/win32\""