fbc/clang: kludgy workaround to fix clang error when compiling with -e

The error is "indirect goto in function with no address-of-label expressions"
See https://bugs.llvm.org/show_bug.cgi?id=18658

changelog.txt

@@ -55,6 +55,7 @@ Version 1.20.0
 - sf.net #659: Keep the stack 16-byte aligned on linux-x86, android-x86 and darwin-x86 to comply with ABI; fixes crashes when external libraries use SSE
 - rtlib: win32/win64: MULTIKEY() on consoles track console focus, remove the 'FindWindow' logic for console windows and handle FOCUS_EVENT message to track focus (adeyblue)
 - rtlib: win32/win64: MULTIKEY() always returns true; don't call GetAsyncKeyState(0), seem that in windows terminal, dragging a console tab out of the terminal window triggers key 0 and is never reset resulting in MULTIKEY() always returning true
+- fbc: when compiling with "-e -gen clang", work around a "indirect goto in function with no address-of-label expressions" clang error
 
 
 Version 1.10.2

src/compiler/ir-hlc.bas

@@ -4000,6 +4000,16 @@ private sub _emitProcBegin _
 	hWriteLine( "{" )
 	sectionIndent( )
 
+	if( (env.clopt.backend = FB_BACKEND_CLANG) and (env.clopt.errorcheck = TRUE) ) then
+		'' Compiling with -e
+		'' Work around an error clang unnecessarily throws if a function
+		'' contains a computed goto but no address-of-label operator.
+		'' See https://bugs.llvm.org/show_bug.cgi?id=18658
+		'' (TODO: We emit computed gotos for RESUME/ON ERROR GOTO
+		'' support (-ex) but also unnecessarily use them to terminate
+		'' the program after fb_ErrorThrowAt when compiled only with -e)
+		hWriteLine( "_unusedlabel: ; void *_llvmbug18658 = &&_unusedlabel;" )
+	end if
 end sub
 
 private sub _emitProcEnd _