llvm12: multiple fixes.

- only disable sanitizer for arm*-musl. the template erroneously
  disabled sanitizer support for all musl targets.
- add libexecinfo-devel to depends, since applications statically
  linking llvm will require it
- fix the xray-ppc64 patch, pointed out by sgn

srcpkgs/llvm12/files/patches/compiler-rt/compiler-rt-xray-ppc64-musl.patch

@@ -44,7 +44,7 @@
 +        if (!ret) {
 +          continue;
 +        }
-+        ret += sizeof("timebase" - 1);
++        ret += sizeof("timebase") - 1;
 +        ret = strchr(ret, ':');
 +        if (!ret) {
 +          continue;

srcpkgs/llvm12/template

@@ -1,7 +1,7 @@
 # Template file for 'llvm12'
 pkgname=llvm12
 version=12.0.0
-revision=1
+revision=2
 wrksrc="llvm-${version}.src"
 build_style=cmake
 configure_args="
@@ -60,6 +60,7 @@ python_version=3
 if [ "$XBPS_TARGET_LIBC" = "musl" ]; then
 	configure_args+=" -DLIBCXX_HAS_MUSL_LIBC=YES"
 	makedepends+=" libexecinfo-devel"
+	depends+=" libexecinfo-devel"
 fi
 
 # "operand out of range" assembler failures
@@ -233,19 +234,16 @@ post_patch() {
 			;;
 	esac
 
-	# some sanitizer currently only on x86_64 stuff needs backtrace
 	case "$XBPS_TARGET_MACHINE" in
-		x86_64-musl)
+		x86_64-musl) # some sanitizer currently only on x86_64 stuff needs backtrace
 			vsed -i 's,# Set common link flags.,list(APPEND SANITIZER_COMMON_LINK_LIBS execinfo),' \
 				${wrksrc}/projects/compiler-rt/CMakeLists.txt
 			;;
+		arm*-musl) # sanitizer code is broken on arm*-musl since it duplicates some libc bits
+			vsed -i 's/set(COMPILER_RT_HAS_SANITIZER_COMMON TRUE)/set(COMPILER_RT_HAS_SANITIZER_COMMON FALSE)/' \
+				${wrksrc}/projects/compiler-rt/cmake/config-ix.cmake
+			;;
 	esac
-
-	# sanitizer code is broken on arm*-musl since it duplicates some libc bits
-	if [ "$XBPS_TARGET_LIBC" = "musl" ]; then
-		vsed -i 's/set(COMPILER_RT_HAS_SANITIZER_COMMON TRUE)/set(COMPILER_RT_HAS_SANITIZER_COMMON FALSE)/' \
-			${wrksrc}/projects/compiler-rt/cmake/config-ix.cmake
-	fi
 }
 
 pre_configure() {