fix clang version check

As 56f87dac says, this is about clang 9, not clang 8.

Change-Id: I2978d2235c7eb3ad438082f7b08a1bd68977ed6f
Reviewed-on: https://gerrit.libreoffice.org/72974
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/compat.hxx

@@ -241,7 +241,7 @@ inline const clang::Expr *getSubExprAsWritten(const clang::CastExpr *This) {
 }
 
 inline bool isExplicitSpecified(clang::CXXConstructorDecl const * decl) {
-#if CLANG_VERSION >= 80000
+#if CLANG_VERSION >= 90000
     return decl->getExplicitSpecifier().isExplicit();
 #else
     return decl->isExplicitSpecified();
@@ -249,7 +249,7 @@ inline bool isExplicitSpecified(clang::CXXConstructorDecl const * decl) {
 }
 
 inline bool isExplicitSpecified(clang::CXXConversionDecl const * decl) {
-#if CLANG_VERSION >= 80000
+#if CLANG_VERSION >= 90000
     return decl->getExplicitSpecifier().isExplicit();
 #else
     return decl->isExplicitSpecified();