Introduce TERMUX_PKG_QUICK_REBUILD

This new variable is extremely useful when iterating on creating a large package,
as otherwise you have to wipe the source and rebuild each time you make a mistake
with the patches or build.sh script.

Simply set TERMUX_PKG_QUICK_REBUILD=true in build.sh if a build fails and then the
TERMUX_PKG_SRCDIR and TERMUX_PKG_BUILDDIR will not be touched when you rebuild,
including that the patches will not be applied again. When you're done iterating,
diff for any new patches, save them, and remove this variable before rebuilding
from scratch, hopefully for the last time. ;)

An example is shown for the giant libllvm package, where other modifications are
also excluded if this variable is set.

packages/libllvm/build.sh

@@ -58,9 +58,11 @@ TERMUX_PKG_HAS_DEBUG=false
 # common.min.50.ompt.optional should be common.deb.50.ompt.optional when doing debug build
 
 termux_step_post_extract_package() {
+	if [ "$TERMUX_PKG_QUICK_REBUILD" != "true" ]; then
 		mv clang-${TERMUX_PKG_VERSION}.src tools/clang
 		mv lld-${TERMUX_PKG_VERSION}.src tools/lld
 		mv openmp-${TERMUX_PKG_VERSION}.src projects/openmp
+	fi
 }
 
 termux_step_host_build() {
@@ -72,9 +74,11 @@ termux_step_host_build() {
 }
 
 termux_step_pre_configure() {
+	if [ "$TERMUX_PKG_QUICK_REBUILD" != "true" ]; then
 		mkdir projects/openmp/runtime/src/android
 		cp $TERMUX_PKG_BUILDER_DIR/nl_types.h projects/openmp/runtime/src/android
 		cp $TERMUX_PKG_BUILDER_DIR/nltypes_stubs.cpp projects/openmp/runtime/src/android
+	fi
 
 	cd $TERMUX_PKG_BUILDDIR
 	export LLVM_DEFAULT_TARGET_TRIPLE=$TERMUX_HOST_PLATFORM

scripts/build/termux_step_patch_package.sh

@@ -6,6 +6,7 @@ termux_step_patch_package() {
 	if [ "$TERMUX_DEBUG" = "true" ]; then
 		DEBUG_PATCHES=$(find $TERMUX_PKG_BUILDER_DIR -mindepth 1 -maxdepth 1 -name \*.patch.debug)
 	fi
+	if [ "$TERMUX_PKG_QUICK_REBUILD" != "true" ]; then
 		# Suffix patch with ".patch32" or ".patch64" to only apply for these bitnesses:
 		shopt -s nullglob
 		for patch in $TERMUX_PKG_BUILDER_DIR/*.patch{$TERMUX_ARCH_BITS,} $DEBUG_PATCHES; do
@@ -14,4 +15,5 @@ termux_step_patch_package() {
 				patch --silent -p1
 		done
 		shopt -u nullglob
+	fi
 }

scripts/build/termux_step_setup_variables.sh

@@ -133,6 +133,7 @@ termux_step_setup_variables() {
 	TERMUX_CMAKE_BUILD=Ninja # Which cmake generator to use
 	TERMUX_PKG_HAS_DEBUG=true # set to false if debug build doesn't exist or doesn't work, for example for python based packages
 	TERMUX_PKG_METAPACKAGE=false
+	TERMUX_PKG_QUICK_REBUILD=false # set this temporarily when iterating on a large package and you don't want the source and build directories wiped every time you make a mistake
 
 	unset CFLAGS CPPFLAGS LDFLAGS CXXFLAGS
 }

scripts/build/termux_step_start_build.sh

@@ -128,15 +128,21 @@ termux_step_start_build() {
                         -e "s|@TERMUX_ARCH@|$TERMUX_ARCH|g" > $TERMUX_PREFIX/bin/llvm-config
                         chmod 755 $TERMUX_PREFIX/bin/llvm-config
 	fi
+	if [ "$TERMUX_PKG_QUICK_REBUILD" != "true" ]; then
 		# Following directories may contain files with read-only permissions which
 		# makes them undeletable. We need to fix that.
 		[ -d "$TERMUX_PKG_BUILDDIR" ] && chmod +w -R "$TERMUX_PKG_BUILDDIR"
 		[ -d "$TERMUX_PKG_SRCDIR" ] && chmod +w -R "$TERMUX_PKG_SRCDIR"
 
-	# Cleanup old state:
+		# Cleanup old build state:
 		rm -Rf "$TERMUX_PKG_BUILDDIR" \
-		"$TERMUX_PKG_PACKAGEDIR" \
-		"$TERMUX_PKG_SRCDIR" \
+			"$TERMUX_PKG_SRCDIR"
+	else
+		TERMUX_PKG_SKIP_SRC_EXTRACT=true
+	fi
+
+	# Cleanup old packaging state:
+	rm -Rf "$TERMUX_PKG_PACKAGEDIR" \
 		"$TERMUX_PKG_TMPDIR" \
 		"$TERMUX_PKG_MASSAGEDIR"