Promote llvm-cov to a standalone option

Introduce WITH_/WITHOUT_LLVM_COV to match GCC's WITH_/WITHOUT_GCOV.
It is intended to provide a superset of the interface and functionality
of gcov.

It is enabled by default when building Clang, similarly to gcov and GCC.

This change moves one file in libllvm to be compiled unconditionally.
Previously it was included only when WITH_CLANG_EXTRAS was set, but the
complexity of a new special case for (CLANG_EXTRAS | LLVM_COV) is not
worth avoiding a tiny increase in build time.

Reviewed by:	dim, imp
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D142645

lib/clang/libllvm/Makefile

@@ -664,7 +664,7 @@ SRCS_MIN+=	Passes/PassBuilder.cpp
 SRCS_MIN+=	ProfileData/Coverage/CoverageMapping.cpp
 SRCS_MIN+=	ProfileData/Coverage/CoverageMappingReader.cpp
 SRCS_MIN+=	ProfileData/Coverage/CoverageMappingWriter.cpp
-SRCS_EXT+=	ProfileData/GCOV.cpp
+SRCS_MIN+=	ProfileData/GCOV.cpp
 SRCS_MIN+=	ProfileData/InstrProf.cpp
 SRCS_MIN+=	ProfileData/InstrProfReader.cpp
 SRCS_MIN+=	ProfileData/InstrProfWriter.cpp

share/mk/src.opts.mk

@@ -119,6 +119,7 @@ __DEFAULT_YES_OPTIONS = \
     LIB32 \
     LIBPTHREAD \
     LIBTHR \
+    LLVM_COV \
     LOCALES \
     LOCATE \
     LPR \
@@ -425,6 +426,7 @@ MK_LLDB:=	no
 .if ${MK_CLANG} == "no"
 MK_CLANG_EXTRAS:= no
 MK_CLANG_FULL:= no
+MK_LLVM_COV:= no
 .endif
 
 #

tools/build/options/WITHOUT_LLVM_COV

@@ -0,0 +1,4 @@
+.\" $FreeBSD$
+Set to not build the
+.Xr llvm-cov 1
+tool.

tools/build/options/WITH_LLVM_COV

@@ -0,0 +1,4 @@
+.\" $FreeBSD$
+Set to build the
+.Xr llvm-cov 1
+tool.

usr.bin/clang/Makefile

@@ -17,7 +17,6 @@ SUBDIR+=	lli
 SUBDIR+=	llvm-ar
 SUBDIR+=	llvm-as
 SUBDIR+=	llvm-bcanalyzer
-SUBDIR+=	llvm-cov
 SUBDIR+=	llvm-cxxdump
 SUBDIR+=	llvm-cxxfilt
 SUBDIR+=	llvm-diff
@@ -44,7 +43,10 @@ SUBDIR+=	lld
 .endif
 .if ${MK_LLDB} != "no"
 SUBDIR+=	lldb
-.endif # MK_LLDB
+.endif
+.if ${MK_LLVM_COV} != "no"
+SUBDIR+=	llvm-cov
+.endif
 .endif # TOOLS_PREFIX
 
 SUBDIR_PARALLEL=